Systems, methods and devices for in vivo monitoring of a localized response via a radiolabeled analyte in a subject

ABSTRACT

System for analyzing an in vivo response of a subject include a radiation detector for detecting radiation present in at least one localized solid tissue region of interest in a subject associated with internal activity of an administered quantity of an analyte comprising at least one of C-14 labeled glucose, a C-14 labeled constituent thereof, and a C-14 labeled glucose derivative, in the at least one solid tissue region of interest over a desired time interval of interest; and a reader in communication with the implantable detector for collecting radiation data from the detector associated with the detected radiation to determine at least one of the following; the in vivo dynamic, kinetic, and metabolic response of the subject.

RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.10/127,207 filed Apr. 22, 2002, which claims priority from U.S.Provisional Patent Application Ser. No. 60/285,923, filed Apr. 23, 2001,the contents of which are hereby incorporated by reference as if recitedin full herein.

FIELD OF THE INVENTION

The present invention is related to systems and methods for monitoringradiation and/or metabolic activity in a subject.

BACKGROUND OF THE INVENTION

One of the major problems in the management of the cancer patient is thepredictability or determination of therapy response prior to theinitiation of treatment. This can be particularly important for thepatient receiving chemotherapy. The conventional approaches in thedetermination of the treatment protocol (to establish a treatment agentor drug(s) regimen) to be used in the treatment of specific tumor typeremains largely empirical. That is, the conventional therapeuticapproach is to utilize what is considered to be the most effectivetreatment as determined by prospective randomized trials across asampled population. This approach overlooks the fact that, as eachpatient is different, so is each patient's tumor and/or response to thetreatment selected. The biological and physiological uniqueness of eachpatient is not considered nor is the potential for an individualizedtherapeutic approach. See generally Kastrissios et al., Screening forSources of Interindividual Pharmacokinetic Variability in AnticancerDrug Therapy: Utility of Population Analysis, Cancer Investigation,19(1), 57-64 (2001).

Both the need for and potential benefits of a predictive test for apatient's response to a particular treatment protocol, particularly forthe cancer patient, have long been recognized. The benefits include (a)an increased chance for tumor response from initial effective therapy,(b) a reduction in the potential for development of resistant cells whenless effective therapy is given (c) a decreased morbidity associatedwith non effective therapy, and (d) an improved probability of cure orpositive outcome with the timely administration of effective therapy. Itis generally accepted that the initial treatment approach is the mostimportant to obtain the best tumor response. Second and third linetherapies are typically less effective and primarily palliative.Therefore, the availability of a method to determine the mostappropriate and effective drug (s) prior to the initiation of therapymay allow for a maximum response. That is, if, for a given tumor,several drugs have been shown to be effective in large clinical trials,the question as to which one (s) to use in a particular patient can beimportant. Since, as noted above, differences do exist betweenindividual tumors of the same site, choosing the most effectivetherapeutic agents should increase the likelihood of a beneficialresponse and reduce the chance for the development of a resistant cellpopulation. It may also reduce the possibility of utilizing a particulardrug as a second or third line therapy, when its effectiveness may bereduced because of the development of drug resistant populations.

An important additional benefit to the patient may be a lower morbidityrate than that which is associated with a “try and see” approach (thatis, to “try” a specific regimen and “see” how the patient responds). Aknowledge of effective drugs may reduce the morbidity of therapy, sinceit will offer the patient an increased chance for response and/or reducethe need for second and third line therapies.

The early attempts to establish predictive tests were dependent on theavailability of cell culture techniques and cell lines. The testsincluded evaluation of cell morphology, exclusion of vital dyes, andincorporation of radioactive precursor molecules after incubation oftumor cells with anticancer agents. The primary problem was a lack ofpredictive value in most correlative studies. See, e.g., Yarnell et al.,Drug Assays on Organ Cultures of Biopsies from Human Tumours, Br Med J1964; 2:490-491. More recently, the culture of human tumors was reportedby Hamburger et al., in Primary Bioassay of Human Tumor Stem Cells,Science 1977;197:461-463. Since its introduction, the Human TumorClonogenic Assay (HTCA) has been investigated as a predictive assay forhuman tumors. Contrary to the previously identified assays, inhibitionof cellular proliferation is directly used as the experimental endpoint.In addition, it defines results in terms of chemoresistance andchemosensitivity. The cumulative results of over 2300 correlationsbetween the HTCA and clinical response was reported by Von Hoff et al.in 1990. See Von Hoff et al., Selection of Cancer Chemotherapy for aPatient by an In Vitro Assay Versus a Clinician, JNCI 1990;82:110-116.The results revealed a 69% probability for a patient to have at least apartial response if the tumor specimen is sensitive to the drug invitro. However, if the tumor is resistant in vitro, there appears to bea 91% chance for clinical resistance. The major technical problems withmost clonogenic assays include the lack of growth in 40 to 60% of allspecimens and a relatively long incubation time (generally on the orderof at least 14 days) before results are available. In addition, there isinsufficient data available on the effect of assay-guided chemotherapyon patient survival, and most clinically observed responses are partialresponses.

More recently, a commercially available assay has alleged a 99% accuracyin prediction of clinical failure. The success of the assay purportedlyresults from extended exposure of the patient tumor cells to levels ofchemotherapy agents, which approximate the peak plasma levels attainedafter conventional IV administration. If a patient's cells proliferateafter extended exposure to peak plasma levels of chemotherapy agents,then it can be accurately predicted that these cells will alsodemonstrate resistance to normal exposures in vivo. However, thereported accuracy to predict chemo-sensitivity is only about 60-70%.Moreover, the assay method is not able to address tumor response overtime or in real time. The sample represents the biology of only onepoint in time of the treatment history of each tumor; it does notconsider conditions that effect drug delivery to the tumor, includingpoorly perfused tumors, local areas of hypoxia or acidosis andhost-dependent resistance mechanisms which can cause high false-positiveprediction of in vitro chemo-sensitivity. See Kern D H, TumorChemosensitivity and Chemoresistance Assays, Cancer, 79:7, 1447-1450,1997.

Others have proposed alternative methods such as Single Photon EmissionTomography (SPECT) and Positron Emission Tomography (PET), which havebeen found to be useful for obtaining functional data of tumors whenradiopharmaceuticals are utilized. There are several approaches for theassessment of chemotherapeutic effects that include measurement of tumormetabolism, quantification of pharmacokinetics of radiolabeled drugs andevaluation of multidrug resistance. A commonly used positron emittingradiopharmaceutical for oncological studies is F-18-Fluordeoxyglucose(FDG). FDG is a tracer, which parallels the transport andphosphorylation of glucose into the cell but is then trapped. Therefore,it is used as an estimate for the regional tumor glucose metabolism. Inaddition, FDG is a tracer that shows a preferential accumulation in mostof the tumor types. As a result, therapy monitoring may be performedusing multiple follow-up PET studies where a decrease in tumor uptakecorrelates with clinical response to therapy, and conversely an increaseis indicative of tumor growth. PET can typically be utilized to measurethe kinetics of the drug over a target area in normal tissue and in thevascular system. Generally stated, only 5FU (5-Fluorouracil) has beenfound useful for routine PET scanning. See Kissel et al., Noninvasivedetermination of the arterial input function of an anticancer drug fromdynamic PET scans using the population approach, Med Phys April 1999;26(4):609-15.

In operation, the PET methodology may allow for the direct measurementof radiotracer concentrations and, thus, a quantification of the5-[F-18]FU accumulation. Dimitrakopoulou et al., Studies with PositronEmission Tomography After Systemic Administration of Fluorine-18-Uracilin Patients with Liver Metastases from Colorectal Carcinoma, J Nucl Med,July 1993, 34:1075-1081. When utilized to assess liver metastasis fromthe colon, kinetic data showed different distribution patterns for themetastases, the normal liver parenchyma and the vessels. The normalliver parenchyma has the highest 5-[F-18]FU uptake about 30 minutesafter onset of the infusion of the tracer, followed by a decrease to 25%of the maximum at the end of the acquisition time. The uptake in themetastases was low and relatively constant during the 120-minuteacquisition time. The mean uptake was one-third of the liver uptake atthe same time interval. Two caveats associated with the distributionpattern reflect the difficulty in utilizing one (single) observation indetermining effective therapeutic response. It was observed that theearly 5-FU uptake is primarily determined by the intracellular uptake ofnon-metabolized 5-FU. Late 5-[F-18]FU uptake values, e.g., 120 minutesafter onset of the 5-FU application, are used as a prognostic parameterfor therapy response, since the data obtained from that time intervalare most likely to mirror the therapeutically active fraction of thedrug. In addition, 5-[F-18]FU studies demonstrated a great variabilityof drug uptake in liver metastases even in the same patient, which mayexplain the low response rates and the variability in response totherapy. The 5-[F-18]FU concentration as measured with PET prior toonset of 5-FU chemotherapy is predictive of therapy outcome, since onlya high 5-FU trapping in the metastasis is correlated with regression,while low 5-FU concentration are not capable of preventing tumor growthduring chemotherapy.

PET can also be used to study mechanisms of drug resistance by employinga combination of O-15 labeled water and 5-[F-18]FU. The former has beenused to study the transport system and identified a difference between apassive and active energy-dependent transport systems. Enhanced 5-FUtrapping was noted in 70% of these lesions. Since only tumor lesionswith an energy-dependent transport system of 5-FU are likely to respondto 5-FU therapy, this information is believed to be of clinical valuefor the individualization of the therapeutic protocol. PET can be usedto select those patients with metastases possessing an active 5-FUtransport system, which can aid the oncologist to direct therapy bymodifying the treatment protocol.

Multidrug resistance (MDR) occurs when cells appear to overcome thecytotoxic effect of chemotherapy. Cytotoxic drugs are rapidlyeliminated, especially in cells with a high concentration ofP-glycoprotein (Pgp), a transmembrane drug flux. Tumors from the colon,kidney, liver and pancreas frequently express the Pgp at high levels.Studies by Piwnica-Worms et al. reported on the use of Tc-99m-sestamibi,a synthetic organotechnetium complex, that can act both as a substratefor Pgp and can act as a marker for the expression of Pgp. SeePiwnica-Worms et al., Functional Imaging of Multidrug-resistantP-Glycoprotein with an Organotechnetium Complex, Cancer Res 53, 977-984,1993. A high Sestamibi accumulation in the tumor correlated with a lowPgp expression and a good prognosis for chemotherapy. Despite theseadvances and observations, there are limitations of PET methodology.Practically speaking, this evaluation method would potentially beavailable to only a limited number of patients since it can be timeconsuming, expensive and impractical for application, not only to everypatient, but on multiple occasions. Secondly, PET scans cannotdiscriminate metabolites. In order to improve the interpretation of thePET data, Nuclear Magnetic Resonance Spectroscopy (NMRS) has also beenused in some patients.

Following the observation in 1984 by Stevens et al., 5-Flourouracilmetabolism monitored in vivo by ¹⁹ F NMR, Br J Cancer 1984, 50:113-117,who showed that 19F-NMRS could detect 5-FU in the liver of mice, thework was extended to observations in the tumors of rats and mice. SeeWolf et al., Tumor trapping of 5-fluorouracil: In vivo ¹⁹ F NMRspectroscopic pharmacokinetics in tumor-bearing humans and rabbits, ProcNatl Acad Sci USA, January 1990, 87:492-496. In 1990, Presant et al.reported their initial observations on the clinical experience with NMRSin 11 patients. They described a “trapped” pool of intra-tumoral 5-FU,defined as a pool of 5-FU whose disappearance half-life (T_(1/2)) islonger than its T_(1/2) in peripheral blood. They also presentedinformation on the correlation between the T_(1/2) of 5-FU in tumors andanti-tumor response to 5-FU. Generally stated, they found that the sixpatients with T_(1/2) of greater than 20 minutes responded tochemotherapy and that the converse was also true. More recently, Presantet. al., in Enhancement of Fluorouracil Uptake in Human Colorectal andGastric Cancers by Interferon or by High-Dose Methotrexate: An In VivoHuman Study Using Noninvasive ¹⁹ F-Magnetic Resonance Spectroscopy, JClin Oncol 18:255-261; 2000, reported that the in vivo modulation of thetumoral pharmacokinetics of 5-FU could be measured non-invasively by19F-MRS and suggested that such information correlates with subsequentclinical outcomes. Further, they suggested that interferon (IFNa-2a) andhigh-dose methotrexate could increase the intratumoral 5-FU in somepatients.

31P/NMR spectra contain peaks from nucleoside triphosphates (NTP),phosphocreatine (PCr), and inorganic phosphates (Pi) and can thereforeprovide information about tumor energy status. The potential of 31P/NMRspectroscopy for evaluating the effect of treatment (radiation andhyperthermia) on sarcomas has been studied by Dewhirst et al. Dewhirstet al., Soft-Tissue Sarcomas: MR Imaging and MR Spectroscopy forPrognosis and Therapy Monitoring, Radiology 174:847-853, 1990. Theypurportedly observed a relationship between treatment-induced decreasein ATP/Pi with the probability of development of necrosis and in arelated study showed an increase in oxygenation after treatmentcorrelated with the amount of tumor necrosis. Another example of anapplication of 31P/NMR spectroscopy is in the monitoring of biochemicalinhibition of specific metabolic pathways. This inhibition is designedto enhance tumor response to radiation and chemotherapy. Agents such as2-deoxyglucose, lonidamine, 6-aminonicotinamide (6AN) can inhibitbiochemical pathways and enhance responses to chemotherapy andradiation. Koutcher et al. (in Koutcher et al., Potentiation of a ThreeDrug Chemotherapy Regimen by Radiation, Cancer Res 53:3518-3523, 1993)observed changes in spectra of mammary carcinoma before and aftertreatment with a 3-drug combination. The observed changes were used todetermine the timing between the drugs and radiation based on when tumormetabolism was maximally inhibited. While the drugs alone induced nocomplete responses and radiation only induced a single ( 1/20) “completeresponse” (CR), the combination of the drugs and radiation (administeredwhen the NMR data demonstrated maximal metabolic inhibition) yielded a65% CR rate and a 25% durable (<1 year) CR rate, without furthertreatment.

Several groups have proposed the use of intraoperative radiation probesfor the purpose of identifying cancerous regions in the body. See e.g.,Zanzonico et al., The intraoperative gamma probe: basic principles andchoices available, Semin Nucl Med 30 (1), pp. 33-48 (January 2000);Barber et al., Comparison of NaI(T1), CdTe, and HgI2 surgical probes:physical characterization, Med. Phys.; 18(3), pp. 373-381 (May-June1991); and Hoffman et al., Intraoperative probes and imaging probes, EurJnl. Nucl. Med. 26(8), pp. 913-935 (August 1999). These techniques canbe characterized as belonging to one of two primary applications:radioimmunoguided surgery (RIGS) and sentinel node detection. It isbelieved that the RIGS applications may be generally described asradiolabeling an antibody specific to a target tumor and then probing inthe operational field with a radiation detector to evaluate which tissuemay be suspect. It is believed that this technique can provide betterlocalization than is available with SPECT (Single Photon EmissionComputed Tomography).

The sentinel node detection techniques can be described as using aninjection of a radiolabeled substance into a tumor and then recording orevaluating the “downstream” activity of the radiolabeled substance todetermine the degree of lymph node involvement. A clinician can use apen-like gamma probe to trace or detect the signal associated with theradioactivity of the lymph nodes (such as during a surgical procedure).

It is also known that there are changes in glycolysis in normal versustumor cells. The facilitative glucose transporters (GLUT 1-5 and 7) havebeen reported as proteins that regulate transport of glucose from theblood to cytoplasm. These proteins are passive transporters and, thus,provide glucose to the interior of a cell if a concentration gradientexists. As previously suggested, increased uptake of glucose by cancercells may be due to an up-regulation of the GLUT genes responsible forthe proteins. Because transport of glucose by these transmembraneproteins is passive, the concentration in the cytoplasm is kept belowthe level in the interstitial fluid. This means that glycolysis canaccelerate to keep up with the process and to attempt to maintain thedesired internal cell level or transmembrane concentration gradient.Therapies that disrupt a key element of glycolysis may arrest the aviduptake of glucose by tumors by reducing the transmembrane concentrationgradient. [18F]FDG has been used recently to look at alterations inglucose uptake following radiation therapy. This observation may beimportant in assessing the onset of apoptosis due to radiation exposure.Glucose transport has been studied after induction of apoptosis by genetherapy designed for a rat tumor model. [11C]glucose labeled in the 1and 6 carbon positions was used to look at the “pentose cycle.” Thiscycle preferentially selects carbon in the first position andincorporates it into CO₂. Thus, it has been proposed that the ratio ofC1/C6 could be predictive of the staging of gliomas. However, thisproposed evaluation method may be difficult in that there is a low(approximately 5%) amount of glucose entering the pentose cycle andbecause the evaluation method is performed in successive runs (first forC1 and then for C6) with a clinically challenging PET isotope.

Despite the foregoing, there remains a need to provide cost-effectiveand/or alternative methods, systems and devices that can individualizeand customize therapy to improve response and outcome and/or otherwisemonitor therapeutic response or delivery of radiolabeled agents in thebody. There is also a need for methods, systems and devices that canprovide increased information on normal and/or tumor glycosis and/or theimpact of therapies on same.

SUMMARY OF THE INVENTION

The present invention provides methods, systems, devices and computerprogram products for in vivo dynamic monitoring of detected radiationwhich is emitted from localized tissue in a target region of the bodyover a selected response or watch period. Generally described, themonitoring can be carried out as a general metabolic assessment, toevaluate or monitor therapy types (including antibody and pharmaceuticaltherapies) and/or to obtain data and evaluate metabolic, biokineticparameters, or predictor variables associated with the in vivo detectedradiation. The data can be used, inter alia, to: (a) predict or assessthe likelihood that a planned treatment will be effective (before orafter a first or subsequent therapeutic dose is actually administered tothe subject); (b) identify which drug or drugs will provide a suitableclinical response for that subject; (c) monitor intratumoral kinetics;(d) study pharmacokinetics and/or pharmacodynamics; (e) study the impactof modifying agents, treatments, or procedures on drug or antibodyuptake and/or retention or tumor kill or morbidity; (f) measure uptake,trapping, or retention of radiolabeled analytes (for any desiredtreatment, whether drug, antibody, and/or radioimmunology); (g) study anindividual's bio-response to a therapy; (h) exclude certain therapychoices; and (i) to evaluate metabolic activity or behavior.

Operations of certain embodiments can be carried out to assessglycolysis and/or to examine specific therapies with respect to alteredglycolysis or dynamic changes in glycolysis. Such analysis may becarried out by employing [¹⁴C]glucose and/or glucose derivatives as wellas the resulting constituents resulting from the glycolysis or metabolicbiochemical process in the body.

Alternatively, the monitoring may be used to quantitatively measure theradiation dose received at localized tissue in the target region (suchas used for radioimmunotherapy). While in other embodiments, the presentinvention can use the detected radiation to analyze thepharmacokinetics/pharmacodynamics or in vivo performance of certainpharmaceutical grade drugs or drug products or derivatives thereof, aswell as analytes, antibodies, metabolites or other therapeutictreatments in the body.

Advantageously, in certain embodiments, the present invention canprovide cost-effective minimally invasive methods, systems, and devicesthat can evaluate, in substantially real-time, one or more selectedbiokinetic parameters or predictor variables of a subject. Certainembodiments of the devices and systems can be configured to identify thedifferences in response between normal and malignant tissue and/or thedifferences in the physiology and biology of individual tumors (or thesame at different times) and to utilize the identified informationregarding same to develop individualized treatment decisions, and/or topredict therapeutic outcome or to improve tumor response.

Other embodiments may allow improved individualized treatment protocolsbased on an in vivo detected uptake or trapping or other desiredresponse (over a selected time) of a non-therapeutic dose of a drugtypically evaluated before and proximate in time to the delivery of thetherapeutic dose) to predict the response of the subject to atherapeutic dose of a drug in advance of administration thereof. Suchpre-delivery assessment capability may be able to allow an improvedselection of chemical or treatment drug, reducing unnecessaryineffective administration of cytotoxic agents which are unlikely to beclinically effective. Thus, the present invention can identify, bymeasuring detected radiation associated with the uptake and retention ofa radiolabeled or radioactive substance, the sensitivity orreceptiveness of a tumor for a particular treatment, proximate in timeto the planned delivery or administration of same.

Other embodiments gather data during a treatment cycle and evaluate itto determine the likely clinical efficacy based on the detected kineticactivity data.

Certain embodiments of the present invention are directed to methods fordetermining the in vivo clinical efficacy of a treatment in a subject.The method can include the steps of: (a) positioning a sensor in tissuein a region of interest in the body; (b) administering a radiolabeledanalyte to a subject; (c) detecting in vivo from the implanted sensor asignal corresponding to the radiation emitted from the radiolabeledanalyte in the region of interest in the subject; (d) relaying thesignal to a location external of the subject's body; and (e) monitoringthe (relayed) signal over time to determine the response of the subjectto the administered analyte to predict or assess at least one of the invivo clinical efficacy of a selected treatment and/or the metabolicactivity in the region of interest.

In certain embodiments, the radiolabeled analyte may be a C-14 (betaemitter) labeled version of a non-labeled corresponding drug or antibodythat is undergoing pharmacokinetic/pharmacodynamic evaluation inclinical or pre-clinical drug trials (or other drug developmenttesting). In other embodiments, the radiolabeled analtye may be ananalog of a chemotherapeutic agent for cytotoxic cancer treatment suchas, but not limited to, a C-14 labeled chemotherapeutic or cytotoxicagent.

Certain embodiments of the present invention are directed to methods fordetermining the clinical efficacy or the metabolic behavior of thesubject when exposed to a selected pharmaceutical or chemical product ina subject. The method comprises the steps of: (a) administering a firstquantity of a C-14 radiolabeled version of a pharmaceutical product(such as a drug or antibody) to a subject; (b) detecting a signal froman in situ sensor, the signal corresponding to the radiation emitted bythe radiolabeled pharmaceutical product in a region of interest in thesubject; (c) relaying the signal to a location external of the subject'sbody; (d) repeating said detecting and relaying steps over at leastabout 0.25-12 hours; and (e) monitoring the signals over time.

In certain embodiments, the monitoring step can be used to determine themetabolic and/or biokinetic response of the subject to thereby predictor assess the in vivo clinical efficacy or local tissue sensitivity to atherapeutic dose of a pharmaceutical product prior to administrationthereof.

The administrating step can be carried out in vivo and performed suchthat the radiolabeled pharmaceutical product is either delivered locallyto the region of interest (such as via injection thereat) or such thatthe radiolabeled pharmaceutical product is delivered systemically (suchas through a syringe or an intravenous catheter). The C-14pharmaceutical can be provided as a first quantity amount which is lessthan a therapeutic quantity of a corresponding non-radiolabeledpharmaceutical product.

Other embodiments of the present invention are directed to a detectionsystem for detecting radiation emitted from an internally administeredradioanalyte. The system includes at least one radiation sensorconfigured for in vivo operation. The sensor is configured to detectbeta radiation emitted from the radiolabeled analyte or its biochemicalconstituents, in or proximate targeted localized tissue in the body. Thesensor is configured to detect emitted beta radiation, at leastintermittently, over a period of time extending from about 0.25-24 hours(the evaluation period can be proximate in time to and at least beforeeach of a plurality of planned therapeutic treatments which areadministered temporally separate from each other). The system alsoincludes a processor operably associated with (each of) the radiationsensor(s). The processor is configured to receive signal data associatedwith the detected radiation from the sensor. The processor includescomputer program code for monitoring selected in vivo parametersassociated with time-dependent measurement profile and/or the uptakeand/or retention of the radioactive substance in the targeted localizedtissue.

Yet other embodiments of the present invention are directed to computerprogram products for evaluating an individual's response to a plannedcancer treatment regimen, the computer program product comprising acomputer readable storage medium having computer readable program codeembodied in the medium. The computer-readable program code comprising:(a) computer readable program code for receiving a first measurement ofradiation detected in vivo in tissue located about a local targeted sitein the body of a subject, the detected radiation corresponding toradiation emitted from a radioactive or radiolabeled substanceadministered internally to the subject; (b) computer readable programcode for receiving a second measurement of the radiation detected in thetissue located about the targeted site after the first measurement thedetected radiation corresponding to radiation emitted from theradioactive substance or radiolabeled analyte administered internally tothe subject; and (c) computer readable program code for generating atime-dependent measurement profile for evaluating selected parametersassociated with at least one of the uptake and retention of theradioactive or radiolabeled analyte in the localized tissue of thesubject based on the first and second measurements.

In other embodiments, the computer program code can be configured toobtain third and fourth measurements (or more measurements).

Other embodiments are directed to computer program products and methodsfor quantifying the amount of radiation delivered to tissue in atargeted local site in the body of a subject in response to aradioimmunology treatment. The program product can include computerreadable program code for (a) receiving data associated with radiationdetected in vivo in tissue located about a local targeted site in thebody of a subject, (b) computer readable program code for generating atime-dependent measurement profile of the detected radiation at thelocal site; and (c) computer readable program code for evaluating theamount of radiation delivered to the localized tissue based on thetime-dependent measurements.

The detected radiation can be based on internally administered radiationthat is directed as a therapeutic pharmaceutical treatment to a targetregion of interest in the subject. The computer program product caninclude computer program code for initiating the first and secondmeasurements a plurality of times over an active treatment periodextending at least from about 5-10 minutes to 24 hours or more, over oneor a plurality treatments (such as a plurality of radioimmunologytreatment sessions for the treatment of cancerous tumors or tissue).

The detected radiation can be used to confirm delivery of the product tothe targeted site and/or to quantify dose or uptake/retention orresponse of the tumor to the product thereat. Such information may beused for monitoring a selected therapeutic treatment(s). The system orprogram can be configured to detect radiation related to the internalactivity of C-14 labeled glucose. This data or information may also beused for therapeutic assessment and/or monitoring.

Other systems or computer programs can be configured for evaluating anindividual's metabolic activity using an in vivo administered betaradiolabeled analtye or metabolite. The program includes: (a) computerreadable program code for receiving data for a first measurement ofradiation detected in vivo in tissue located about a local targeted sitein the body of a subject, the detected radiation corresponding toradiation associated with a radiolabeled analyte administered internallyto a subject; (b) computer readable program code for receiving data fora second measurement of the radiation detected in the tissue locatedabout the targeted site after the first measurement, the detectedradiation corresponding to radiation associated with the radiolabeledanalyte administered internally to the subject; and (c) computerreadable program code for monitoring the received data over time toevaluate the metabolic activity of the local targeted site.

Other embodiments are directed to a method of quantifying the amount ofradiation delivered to or the metabolic activity of tissue in a targetedlocal site in the body of a subject. The method comprises the steps of:repeatedly detecting radiation in vivo in tissue located about a localtargeted site in the body of a subject over a response window; andevaluating the uptake and retention of radiation in the local site overthe response window to determine the amount of radiation delivered tothe localized tissue based on the detecting step.

Additional embodiments are directed to systems for analyzing in vivometabolic activity of a subject. The system includes detection means fordetecting metabolic kinetic activity in vivo based on the levels ofradiation present in a localized in vivo region of interest responsiveto an internally administered radioanalyte in the subject over a desiredtime interval of interest; and analyzing means for analyzing dataassociated with the detected radiation to determine the in vivometabolic kinetic activity of the subject.

The system may further include a biocompatible radiolabeled analyteconfigured for human or animal administration and the detection meanscan be adapted to detect the concentration activity of the radiolabeledanalyte in the region of interest.

The present invention can acquire data associated with the detectedradiation and generate at least one time-dependent measurement profileof the radioactivity in a localized region of the subject. Thetime-dependent profile can be analyzed to identify or quantify one ormore predictor variables which captures desired informationcorresponding to one or more of the efficacy, performance, activity, orstatus of the radiolabeled substance in the body and/or targeted orlocalized tissue. The predictor variables or parameters can include (butare not limited to) the biological ½ life of the radiolabeled analyte inthe localized tissue, the amount of time the detected radiation is abovea predetermined threshold level, the amount of time that the radiationdetected is increasing, the peak value of the detected radiation, thetime at which the peak radiation level occurs, and the decay rate of thedetected radiation.

The foregoing and other objects and aspects of the present invention areexplained in detail in the specification set forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a method of operation according toembodiments of the present invention.

FIG. 2A is a block diagram of another method of operation according toembodiments of the present invention.

FIG. 2B is a block diagram of an additional method of operationaccording to embodiments of the present invention.

FIG. 2C is an example of a glucose chemical structure that may beradiolabeled according to embodiments of the present invention.

FIG. 2D is a block diagram of another method of operation according toembodiments of the present invention.

FIG. 3 is a block diagram of an additional method of physiologic orbiologic evaluation according to embodiments of the present invention.

FIG. 4A is a schematic illustration of a system employing a wirelesssensor according to embodiments of the present invention.

FIG. 4B is a schematic illustration of a system similar to that shown inFIG. 4A but with an alternate sensor/system configuration (wired)according to embodiments of the present invention.

FIG. 5A is a schematic illustration of a radiation sensor located invivo and associated monitoring system according to embodiments of thepresent invention.

FIG. 5B is a schematic illustration of a detection system according tothe present invention that can be configured as a transcutaneous,intralumen or intracavity catheter or probe-based sensor.

FIGS. 6A-6E are graphs of simulated or predicted radiation activitymeasurements over time or time-dependent measurement profiles which canbe monitored according to embodiments of the present invention. FIGS. 6Aand 6C illustrate time dependent measurement profiles with examples ofsome predictor variables or kinetic parameters. FIG. 6B illustrates thatthe dose can be based on a mathematical integral of the area under thecurve of the measurement profile. FIG. 6E illustrates that a firstderivative of count per second can be mathematically derived for doseevaluation. FIG. 6D illustrates that a plurality of time-dependentprofiles can be obtained on the localized tissue at different time orevaluation periods to obtain substantially real time or dynamicinformation so as to assess the status or receptiveness/sensitivity orperformance of the drug at the localized tissue.

FIG. 6F is a flow diagram of a method for using calculated kineticfactors or one or more predictive variables to determine whether abiokinetic response is favorable in making therapeutic treatmentdecisions according to embodiments of the present invention.

FIG. 7 is a cross-sectional view of an implantable radiation sensoraccording to embodiments of the present invention.

FIG. 8A is a partial cross-sectional view of an alternate embodiment ofa radiation sensor according to the present invention.

FIG. 8B is a partial cross-sectional view of an additional embodiment ofa radiation sensor according to the present invention.

FIG. 9A is a schematic illustration of a sensor with a plurality ofradiation sensing probes according to embodiments of the presentinvention.

FIG. 9B is a schematic illustration of a sensor with a plurality offiber optic leads used to relay light according to embodiments of thepresent invention.

FIG. 10A is a schematic of a fiber optic system used to evaluate betaspectroscopy signals according to embodiments of the present invention.

FIG. 10B is a schematic of an implantable wireless system used to obtaindata associated with internally administered beta radiation.

FIG. 10C is a greatly enlarged front view of an implantable wirelesssensor configured to detect internally administered beta radiationaccording to embodiments of the present invention.

FIG. 11A is a graph of an exemplary in vivo response profile of theconcentration or uptake over time of a radiolabeled analyte according toembodiments of the present invention.

FIG. 11B is a graph of another exemplary in vivo response profile of theconcentration or uptake over time of a radiolabeled analyte according toembodiments of the present invention.

FIG. 11C is a graph of a statistical model of predicted values comparedto observed results of the flank/inguinal probe region of FIG. 11Baccording to embodiments of the present invention.

FIG. 11D is a graph of additional exemplary in vivo response profiles ofthe counts over time of a radiolabeled analyte according to embodimentsof the present invention.

FIG. 12A is a graph of another exemplary in vivo response profile of theconcentration or uptake over time of a radiolabeled analyte according toembodiments of the present invention.

FIG. 12B is a graph of an additional exemplary in vivo response profileof the concentration or uptake over time of a radiolabeled analyteaccording to embodiments of the present invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention will now be described more fully hereinafter withreference to the accompanying figures, in which preferred embodiments ofthe invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Like numbers refer to like elementsthroughout. Layers may be exaggerated for clarity. In the figures,broken lines, unless stated otherwise, represent optional steps orfeatures.

As will be appreciated by one of skill in the art, the present inventionmay be embodied as a method, data processing system, or computer programproduct. Accordingly, the present invention may take the form of anentirely hardware embodiment, an entirely software embodiment or anembodiment combining software and hardware aspects. Furthermore, thepresent invention may take the form of a computer program product on acomputer-usable storage medium having computer-usable program code meansembodied in the medium. Any suitable computer readable medium may beutilized including hard disks, CD-ROMs, optical storage devices, atransmission media such as those supporting the Internet or an intranet,or magnetic storage devices.

Computer program code for carrying out operations of the presentinvention may be written in an object oriented programming language suchas Java®, Smalltalk or C++. However, the computer program code forcarrying out operations of the present invention may also be written inconventional procedural programming languages, such as the “C”programming language. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer. In the latter scenario, theremote computer may be connected to the user's computer through a localarea network (LAN) or a wide area network (WAN), or the connection maybe made to an external computer (for example, through the Internet usingan Internet Service Provider).

The present invention is described below with reference to flowchartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products according to embodiments of the invention. Itwill be understood that each block of the flowchart illustrations and/orblock diagrams, and combinations of blocks in the flowchartillustrations and/or block diagrams, can be implemented by computerprogram instructions. These computer program instructions may beprovided to a processor of a general purpose computer, special purposecomputer, or other programmable data processing apparatus to produce amachine, such that the instructions, which execute via the processor ofthe computer or other programmable data processing apparatus, createmeans for implementing the functions specified in the flowchart and/orblock diagram block or blocks.

These computer program instructions may also be stored in acomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meanswhich implement the function specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,processor (such as a digital signal processor), or other programmabledata processing apparatus to cause a series of operational steps to beperformed on the computer or other programmable apparatus to produce acomputer implemented process such that the instructions which execute onthe computer or other programmable apparatus provide steps forimplementing the functions specified in the flowchart and/or blockdiagram block or blocks.

Generally described, in certain embodiments, the proposed device andsystems can be used to obtain data and/or measure or monitor theemission of radiation from radiolabeled analytes. The term “radiolabeledanalytes” includes, but is not limited to, radiolabeled antibodies,radiolabeled antigens, radiolabeled nucleic or amino acids, otherradiolabeled endogenous substances or molecules such as glucose or othernaturally occurring substances and/or their derivatives, metabolites, orconstituents, and radiolabeled exogenous substances and/or moleculessuch as pharmaceutical drugs or derivatives thereof, and the like, aswell as combinations of the above. The emitted radiation from theradiolabeled analyte(s) can be detected in vivo from tissue in target orlocalized region(s) in the body. This detected and monitored radiationcan provide information on one or more of the metabolic activity in thelocalized region, tissue, or cells, thepharmacokinetics/pharmacodynamics of a corresponding non-radiolabeledanalyte or substance, the likelihood of the uptake and the retention ofcertain chemotherapeutic drugs in the localized region or tissue, and/ora substantially real-time or kinetic analysis of the biological statusor metabolism and/or proliferation of malignant and/or normal cells inthe localized tissue or region at desired points in time. Theradiolabeled version of the non-radiolabeled analyte can be formulatedto have the same or substantially similar pharmacological or biochemicalactivity as the parent analyte.

Such systems and methods can be used to obtain and/or analyze data orphysical quantities from the living body to provide intermediate datathat may be provided to a clinician or researcher for furtherconsideration. The detection can be carried out at multiple sites abouta region of interest or at a plurality of different spaced apart sitesin the body. The systems, methods, and operations of the presentinvention may be carried out to monitor for longer times overconventional systems, the biological or physiological impact of aselected therapy (or combinations of therapies) on a target disease,disorder, or condition of the body (pharmacodynamics) in addition to thein vivo levels, activity, retention, uptake, delivery, etc., of one (ormore) therapeutic agents (pharmacokinetics).

Certain embodiments of the systems and methods of the present inventionmay be used with any analyte which can be radiolabeled or maderadioactive, including, but not limited to, as noted above, endogenousmaterial that can be radiolabeled and re-introduced to the subject, orexogenous material. As also noted above, suitable analytes can includeradiolabeled versions of nuclides, pharmaceuticals and derivativesthereof, antibodies, antigens, proteins, peptides, amino acids, nucleicacids, glucose and metabolites and derivatives thereof. The radiolabeledanalyte may be a genetically engineered substance, which has asite-specific or tumor or tissue specific delivery target, adifferentiation antigen, or an analyte which can be activated upondelivery to a particular region or tissue or which can otherwise belocally “activated” or targeted. The radiolabeled analyte or substancemay be selected based on its presence or expression, i.e., aradiolabeled marker associated with a disease or cancer in the region orat the targeted site, such as an over or under expression of an antigen,antibody, peptide, protein, enzyme, amino acid or other endogenousanalyte, or other genome or phenotype(s) criteria or behavior. Thus, itis contemplated that radioactive monitoring for dynamic amounts of themarker or antigen expression can provide valuable internal real time ordynamic information about cellular activity.

The term “glucose derivative” includes glucose molecules with a modifiedglucose chemical structure that is biocompatible and can bebiochemically processed by the body. Examples of glucose derivativesinclude, but are not limited to, dextraglucose (D-glucose), and2-deoxyglucose (2-DG).

Examples of marker or expression-based evaluation of antigens/antibodies(which may be radiolabeled) include those used in cancer evaluationand/or treatment. Examples of tumor-associated antigens of interest mayinclude the CD-20 antigen (on B lymphocytes) for which treatment mayinclude agents having antibodies to the CD-20 antigen and humanepidermal growth factor (HER2) associated with some breast tumors. It isnoted that HERCEPTIN may be radiolabeled and is currently approved forHER2 breast cancer treatment.

It is contemplated that other biomaterials may also be suitable to carryout operations of the present invention. Examples of potentiallysuitable biomaterials may include, but are not limited to, mixedcultures containing tumor cells and blood-derived lymphocytes (which maybe from the patient him or herself) to produce cytolytic T lymphocytes(CTL) (or CTL clones or autologous CTL), that lyse the autologous tumorcells (which may be used in connection with melanoma, renal, bladder,head and neck carcinomas, non-small lung cancer, and the like). Otherpotential antigens/antibodies of interest include MAGE-1, MAGE-3, BAGE,GAGE-1, and GAGE-3. See, e.g., UCL Christian de Duve Institute ofCellular Pathology, Ludwig Institute For Cancer Research, URLwww.Icp.ucl.ac.be/report95/licr95.html.

In any event, the radiolabeled analyte may be combined with othersubstances and formulated for the desired delivery (injection,intraveneous, subcutaneous, etc. . . . ) to produce the desiredcomposition and/or bolus. In certain embodiments, the analyte can beformulated into a liquid solution. The solution can be formulated todilute the concentration of the radiolabeled constituent or ingredientor to provide other desired biocompatible materials. Examples ofsuitable radiolabeled or radioactive substances will be discussedfurther below. The radioactive or radiation label can be gamma, alpha,or beta radiation, depending on the application.

The term “subject,” according to the present invention, includessubjects belonging to the animal kingdom, and are preferably mammaliansubjects (e.g., humans, canines, felines, bovines, caprines, ovines,equines, rodents, porcines, and/or lagomorphs), and more preferably arehuman subjects.

In certain embodiments, the analyte is a therapeutic pharmaceutical drugor antibody that is configured to treat a selected physiologic orbiologic condition, impairment, or disease. The radiolabel can beselected or formulated to be substantially transparent so that thenon-radiolabeled version and the radiolabeled version of the sameanalyte has substantially the same biochemical activity in the bodyand/or the radiolabeled version does not interfere with the intendedtherapeutic, physiologic, or biologic reaction in the body. As such, theradiolabeled version of the analyte (or drug or antibody) can be suchthat the radiolabeled version biologically functions or is biochemicallyprocessed in substantially the same manner as a correspondingnon-radiolabeled version. In certain embodiments, the radiolabel doesnot inhibit or interfere with the natural breakdown or reaction of theanalyte and/or its constituents in the body.

The radiolabel can be a beta radiation label, wherein the beta radiationlabel is substantially transparent to the intended therapeuticphysiologic or biologic reaction of the drug in the body. Examples ofbeta-emitting radioactive labels include one or more of C-14, P-32,P-33, I-131, Kr-85, Xe-133, TI-201, Ga-77, F-18, Cs-137, Ca-45, Ca-47,Co-60, Fe-59, Hg-203, Ni-63, Rb-86, Ru-106, Ag-110m, Na-22, S-35, Sr-90,Tc-99, H-3, Zn-65, Cu-64, O-15, N-13, and other positron emitters andbeta particles used therapeutically.

In certain embodiments, the radioactive label is C-14. Carbon is widelyused in drug evaluations and C-14 has a suitably long decay half-lifeand an acceptably short biological half-life for most drugs of interest.The C-14 label can thus be used with a wide variety of pharmaceuticalproducts and is not limited to one particular drug or a small number ofdrugs, thereby allowing for a relatively wide, evaluation model orprotocol for available therapeutic agents.

In certain particular embodiments, the radioactive label may be selectedfor its ability to (a) be used across a wide variety of therapeuticdrugs, (b) generate sufficient signal in the localized tissue in thebody to allow for dynamic and/or quantitative monitoring over a desiredresponse window (of between at least about 5 minutes-30 minutes, andtypically at least 30 minutes-1 hour), and (c) have a biocompatiblebiological half-life with a suitable shelf-life. This is in contrast toconventional evaluation methods, which, as discussed above, employvarious radioactive substances. For example, PET-based methods useradionuclides that emit positrons. F-18 is one common radionuclide usedin these types of procedures; however, fluorine containing drugs ortherapeutic products are not common. Other radioactive labels may alsoonly be useful in a limited number of drugs while others may have anunduly short half-life that, in turn, can limit the amount of data orthe width of the evaluation window over which data can be taken. Stillother radioactive labels may not generate sufficient concentration orsignal levels to allow quantitative evaluation in the body (to generateunfavorably weak signals).

Turning to FIG. 1, in the embodiment shown, a subject can be undergoingtreatment for a cancerous tumor. A quantity of a radiolabeled orradioactive substance (alone or combined with other ingredients orsubstances) is administered to the subject (Block 100). As shown, thequantity and/or radioactive intensity or concentration of the substanceor analyte may be such that it acts as a pre-diagnostic test dose,rather than a therapeutic dose, which is delivered in advance of thetherapeutic dose to assess or predict the clinical efficacy of atreatment prior to delivery of the treatment itself. The radiolabeledanalyte or substance can be delivered either systemically, locally, orboth (Block 105).

In certain embodiments, a small test or diagnostic dose of aradiolabeled substance or analyte such as a C-14 labeled analog of achemotherapy drug or pharmaceutical can be administered to the subjectproximate in time (and/or before) a treatment session (for which anon-radiolabeled version of the pharmaceutical can be used totherapeutically treat the cancer). As used herein, a “small” dose meansa dose which is less than a therapeutic dose. The detected radiation canprovide kinetic or predictive information about the likelihood of thesuccess of the treatment and allow a potential clinician to proceed withthe planned treatment, delay the treatment, exclude one or more of atreatment, or select a different pharmaceutical agent for treatment. Incertain embodiments, the radiolabeled dose can be sized in an amountwhich is about a 0.1%-60%, and can be about 1-10% of that of acorresponding therapeutic dose.

In certain embodiments, the radiolabeled substance or analyte can have aconcentration of about 100-500 nanocuries/cc to about 1-10millicuries/cc (mCi/cc) (the latter typically being more suitable fordirect injection at the target site). In particular embodiments, theconcentration may be from between about 10 μCi (10⁻⁶ Curies) to about 1mCi. The dose may be sized according to weight (children may receivedoses in the lower portion of the range with large adults receivingdoses at or above the typical range).

In certain embodiments, the concentration can be selected such that itcorresponds to whole body doses of about 1-10 milliGray corresponding toconcentrations conventionally used for nuclear medicine scans. In otherembodiments, the radiolabeled analyte or substance can be systemicallydelivered at higher radiation concentrations where it is targeted forthe target site (selective target or site specific activationformulations such as antibodies). In these embodiments, the taggingsystem may be designed to deliver a total dose on the magnitude of about10-99 Grays.

Systemic deliveries may be made by any suitable mode such as via IVintroduction into the vein of the subject. Local deliveries may be madeby injections from a lumen of a syringe or via introduction through atranscutaneous catheter configured to direct the radiolabeled substancesubstantially directly to or proximate to a target region.

Turning again to FIG. 1, the radiation emitted from local tissue (suchas a cancerous tumor) is detected in vivo. The detected radiation can beanalyzed over a selected response period, cycle, or time (s) (Block110). For example, a radiation sensor can be operably configured suchthat it is at least intermittently or periodically activated and may becontinuously operated or monitored to relay information to a clinicianover a time which is proximate to the administration of the radiolabeledanalyte to about 24 hours later. In certain embodiments, the radiationis detected every 30 seconds to every 15 minutes during a portion of thedetection cycle when the detected radiation values change from the priorreading. This shortened interval may be in the early portion of themonitored response cycle (such as in the first 10-60 minutes afterinitiation of the administration of the radiolabeled analyte). Theactivation or detection interval can be automatically extended whenthere is little fluctuation between incremental readings (based on anaverage between more than two readings or the values between twoconsecutive readings). The adjustment between detection intervals may bebeneficial for some embodiments, which may employ wireless implantablesensors to preserve power (and extend operative life). Examples ofparameters which can be monitored or analyzed will be discussed below.

In certain embodiments, which may be particularly suitable forcontinuous mode monitoring (but may also be used otherwise), theradiation levels can be detected and summed until the completion of thetest or at the end of the evaluation/response window. The firstderivative can be mathematically calculated or determined (to providedata on the rate of change of concentration) (FIG. 6E) or the lineshape,profile, or curve of parameters associated with the time-dependentmeasurements can be analyzed to yield the radiation level in the targetissue over time.

Referring again to FIG. 1, a therapeutic treatment type oradministration time can be selected based on the analyzed dataassociated with the detected radiation (Block 120). For example, basedon the detected radiation over the response cycle, a clinician can haveaccess to individualized information concerning the status of thebioactivity of the local tissue, the likelihood of the receptiveness toa desired therapeutic treatment, and/or the likelihood of a suitableuptake and retention of the desired therapeutic agent based on theuptake and retention of the administered radiolabeled analyte. As such,a clinician can select which particular chemotherapeutic agent (oragents) to administer to the subject at that point in time. Similarevaluations can be carried out periodically over the treatment cycle(typically 2 or more different chemotherapy administrations may beperformed over a period of weeks and months). In certain embodiments,the radiolabeled analyte can be administered just proximate to(typically prior to) a planned chemotherapeutic treatment session. Incertain embodiments, the therapeutic administration can be performed inless than 24-48 hours (and before any additional intentional orunintentional perturbation) from the monitored response cycle to reducethe likelihood that the bioactive nature or status of the tissue and,thus, the predicted response, will shift substantially.

In certain embodiments, the clinician may determine that conditions areunfavorable for a therapeutic treatment and delay or exclude thetherapeutic treatment until local conditions improve (thereby reducingthe introduction of cytotoxic drugs when the treatment outcome is likelyto be unfavorable). As such, the data obtained may be used to evaluatewhether to exclude certain potential therapies (including changing orprescribing alternative drug therapies) as it may not be indicated to bea viable treatment for that individual, or to postpone the treatment fora more favorable time.

As the detected radiation values can be monitored over time to determineor assess the present status (i.e., substantially real-time) of thelocalized tissue or evaluate the biokinetic or metabolic or activityresponse and/or the physiological or biological status of the localtissue, the method can be repeated at desired intervals, such asproximate in time to each therapeutic treatment over the activetreatment period (Block 130). The data can be obtained several timesduring a desired monitoring period (such as twice, thrice, four or evenmore times). In certain embodiments, the kinetic data or radiationvalues of interest can be obtained before and after a particulartreatment or active treatment session. Further, a radiolabeled analytemay be administered before and after a therapeutic treatment tofacilitate the detection in vivo of localized response data. This repeatadministration of a radiolabeled analyte may increase the detectabilityof the signal (increase the signal strength) in the body, depending onthe length of the therapeutic treatment, and/or may provide dataregarding the state of the tissue after administration of a therapeuticagent and/or at a desired point in time.

When selecting the therapeutic treatment, the clinician can consider aplurality of different pharmaceutical treatments and/or cytotoxic agentsbased on the evaluated condition or response of the tumor of the subject(Block 125). In addition, combination therapies can be considered toattempt to generate increased receptiveness. For example, heat or anexternally generated and directed radiation dose or other combinationtherapy modality may be desirable to improve the tissue receptiveness.In any event, each of the chemotherapeutic treatment agents orcombinations can be evaluated to select those types that align with ormatch the predetermined associated desired biological and/orphysiological conditions (such as cell proliferation or sensitivityassociated with uptake and/or retention of the radiolabeled analyte inthe tissue) with that of the subject to yield increased clinicaleffectiveness.

Thus, in certain embodiments, the methods and systems may be used todetermine the timing and type of treatment to administer to a subject soas to promote clinical efficacy based on a dynamic or substantiallyreal-time understanding of the physiological or biological status of thetargeted tissue. Other embodiments can evaluate the metabolic activityof the subject and/or to study pharmacokinetics/pharmacodynamics. Forexample, the data can be obtained and evaluated in a manner thatprovides information on the influence and/or impact on metabolicactivity that certain therapies, activities, foods, vitamins, foodsupplements, or environmental exposures, may have on the target regionof interest.

The system can be configured as a minimally invasive device that can, incertain embodiments, employ an implantable wireless or telemetric basedradiation sensor. In other embodiments, the radiation sensor(s) can be acatheter or probe based device and placed transcutaneously or insertedvia a cavity or lumen to the site of interest where a fiber optic (orbundle of fiber optics) acts as the sensor. Exemplary sensor and systemconfigurations will be discussed further below.

FIG. 2A illustrates that, in certain embodiments, a C-14 labeled analytecan be administered to a subject (Block 200). The beta radiation emittedfrom local tissue in the subject responsive to the administeredradiolabeled analyte can be detected in vivo from a radiation sensorpositioned in situ in tissue proximate to a target site in the body. Thedetected radiation can be monitored at desired times in a monitoringperiod (typically generating a signal or over time) (Block 210). Atleast one of the dynamic or kinetic biophysical response or activity(including the physiological or biological condition or response oractivity) of the subject or the pharmacokinetic and/or pharmacodynamicactivity associated with the radiolabeled analyte can be monitored ordetermined or the monitored data can confirm that the radiolabeledanalyte (or biochemical constituent thereof) is delivered to theintended targeted tissue in the subject (Block 220). The data from themonitoring step can be used to assess desired in vivo response oractivity such as, for example, the clinical performance, biophysicalresponse or non-response of the subject, or efficacy of anon-radiolabeled counterpart analyte (Block 221).

The detected radiation may also be calibrated to quantitatively measurethe radiation dose received at the tissue. The calibration can be basedon signal strength or radiation counts detected based on in vitro valuesof levels in tissue or otherwise defined by experimental or clinicalevaluations to correlate the signal to the amount of radiation presentin vivo.

In certain embodiments, the radiolabeled analyte corresponds to aradiolabeled version of a (non-radiolabeled) drug in the discovery phaseof development or evaluation (such as before or during clinical orpre-clinical trials) and is administered to evaluate thepharmacokinetics and/or pharmacodynamics thereof.

FIG. 2B illustrates that, similar to the operations described in FIG.2A, the radiolabeled analyte is a C-14 labeled glucose molecule, alsoknown as [¹⁴C]glucose. The [¹⁴C]glucose can be monitored as it proceedsthrough a biochemical reaction and breaks into metabolic constituentcomponents in the body. The C-14 labeled glucose molecule may includeglucose molecule derivatives such as, but not limited to, 2-deoxyglucose(2-DG), dextra-glucose (D-glucose), or other radiolabeled glucosemolecule derivative suitable for in vivo administration to a subject(Block 230). Data associated with the beta radiation corresponding tothe [¹⁴C]glucose, and/or glucose derivatives, as well as one or more ofits radiolabeled metabolic or biochemical constituents in the subject,which is emitted from targeted localized tissue, is obtained andmonitored over time (Block 240). The dynamic kinetic biophysical and/ormetabolic (that can include one or more of the pharmacodynamic orpharmacokinetic) response in the subject can be determined or evaluatedbased on the obtained data (Block 250).

The position of the C-14 label on the glucose molecule and/or a glucosederivative molecule can be selected based on one or more of a desiredbiochemical breakdown in the body, the desired residence time (longer orshorter) in the body, and/or the desired exit pathway of the C-14radiolabel from the body. It is has been suggested that [3-¹⁴C]— and[4-¹⁴C] versions may release ¹⁴CO₂ earlier in the biochemical reactionprocess while [1-¹⁴C]—, [2-¹⁴C]—, and [6-¹⁴C]— may release ¹⁴CO₂ laterin the process cycle. See, e.g., Hawkins et al., Cerebral glucose usemeasured with [14C] glucose labeled in the 1, 2, or 6 position, AmericanPhysiological Soc., C-170-C173 (1985)(diagramming the fate of C-14 invarious positions of the carbon bonds of a glucose molecule onmetabolism by glycoslysis and the tricarboxylic acid cycle). See also,Hamkens et al., PET in Clinical Oncology, pp. 55-65, Edited by Wieler etal. (Springer, Darmstadt, Germany, 2000) (discussing, describing, andcomparing, the biochemical pathways of the metabolism of glucose and FDG(denotation of the essential enzymes v.i.)). The contents of thesereferences are hereby incorporated by reference as if recited in fullherein. Thus, embodiments of the present invention can selectivelyposition the C-14 label to a desired carbon site on the glucosemolecule.

In certain embodiments, the radiolabel on the glucose or glucosederivative molecule may be expelled from the body based on whatconstituent component the C-14 metabolizes into or biochemically breaksdown into, so that is may be expelled either via respiration (via CO₂),incorporated into the cell, and/or excreted in fluid. As noted above,selectively positioning the C-14 label on a carbon site on the glucosemolecule can cause the body to release the radiolabeled constituent(s)earlier or later in the biochemical process (earlier discharge may alsoprovide faster discharge of the radioactive component from the body).Monitoring the activity associated with the digestion or metabolizedglucose may yield important information on the status of the localizedtissue or tumor site. In contrast, 2-DG, is not metabolized by cells andmay typically remain in the body for several hours to 1 day before it isde-phosphorylated and excreted.

Metabolized glucose data may be analyzed in a relative assessment or inan absolute assessment. For example, the signal data can be compared toabsolute threshold data established from population norms (which may besegmented by population age or gender or disorder) or to relative dataeither normal or tumor data taken on the subject previously. The datacan be used in a quantitative manner to establish concentration,quantity, rates (uptake and discharge), speed of the biochemical cycle,and the like.

In certain embodiments, two different response profiles can begenerated, before and after certain therapies or temporally spaced apartin time, or with different analytes. For example, two response profilescan be taken with different radiolabeled analytes such as, but notlimited to, both the [¹⁴C]glucose and the C-14 labeled 2-DG analyte. Oneor both types of glucose-based data analysis may be able to provideinformation glycolysis and/or the tricarboxylic acid cycle. Suchinformation may indicate normal or abnormal cellular behavior. Forexample, the information may be used to assess when a tumor or site isaerobic (oxygen rich) or anaerobic (oxygen deficient). It is known thattumors have abnormal glucose metabolic activity. Growing tumors candigest or take-in increased amounts of glucose relative to normal tissue(i.e., are hypermetabolic). Thus, the presence of increased amounts ofC-14 glucose during the biochemical process may be representative of agrowing, aerobic, or active tumor. Such information may be able to beused to assess tumor receptiveness to a particular treatment such as acytotoxic agent and/or to indicate that the target region compriseshealthy tissue.

In certain embodiments, operations carried out according to the presentinvention can evaluate whether a given therapy has altered, disrupted,inhibited, or impaired, or promoted, the glycolysis biochemical process.This alteration may be identified earlier in a treatment cycle beforeglucose uptake is substantially altered, potentially providing earlierindications of therapeutic efficacy or influence.

FIG. 2C illustrates an exemplary glucose molecule. The glucose may be inan alpha-pyranose form. Of course, the glucose may also be formulated inother biocompatible forms as is known to those of skill in the art. Asnoted above, one or more of the carbon sites in the glucose molecule maybe replaced with the C-14 tag as desired. Due to the body's ability tometabolize glucose, a plurality of serially administered and/orsuccessive doses (separated over desired time intervals) of theradiolabeled analyte may be used to evaluate a patient's metabolicactivity or tumor status. In certain particular embodiments, the C-14label is selectively chosen for a particular carbon position, such as inpositions C-1, C-2, C-3, C-4, C-6 or combinations thereof. In particularembodiments, the C-14 label can be located at C-3 or C-4 so as topromote metabolization with ¹⁴CO₂ discharge earlier in the biochemicalprocess.

FIG. 2D illustrates a series of operations that may be carried out toobtain data of metabolic activity according to embodiments of thepresent invention. As shown, radiolabeled or tagged glucose or (abiocompatible) glucose derivative is administered to a subject (Block260). Data associated with the administered radiolabeled glucose and/orglucose derivative is obtained as the radiolabeled glucose or glucosederivative is delivered to at least one target region and is taken up inlocalized tissue, and/or metabolized into constituent components in thebody (Block 265). The data can be monitored over time to evaluate themetabolic activity, the pharmacokinetics and/or pharmacodynamics of atleast one target region (Block 270). The data may relate to themetabolic status of a tumor or its biochemical metabolic activity. Incertain embodiments, data can be obtained from two different targetregions, one associated with normal or non-diseased tissue and the otherassociated with abnormal or tumor tissue. Data of the normal versusabnormal or tumor tissue can be obtained and compared as theradiolabeled glucose and/or glucose derivative is taken-up, metabolized,processed and/or transformed, by the body into constituent chemicalcomponents to assess whether there is abnormal or altered behavior oractivity in the tumor or abnormal tissue (Block 266).

In any event, whatever methods of operation and/or analyte selected, thedata can be obtained at discrete points in time and compared to generatea relative assessment of biochemical or metabolic change, efficacy orinefficacy in response to a therapy, and the like. In other embodiments,the data can be used to generate absolute or quantification values ofthe metabolic activity and/or radiation level at the target site(s).

In certain embodiments, data can be collected from a plurality ofdifferent target sites. For example, but not limited, the data can beobtained proximate to (near, adjacent, or in) tumor tissue and proximateto (typically in) normal tissue. In addition, multiple “normal” and/or“target or abnormal” tissue sites of interest may be concurrentlymonitored.

The in vivo detected beta radiation corresponds to radiation emittedfrom localized tissue or regions. The detected radiation is attributedto the uptake and/or retention of the analyte at the localized tissue ata certain point in time or at certain points over time. Selectedparameters associated with the detected radiation can be monitored. Theselected parameters can include one or a plurality of various parameterssuch as the flux, rate or acceleration of change, and/or a parameterhaving been identified as predictive of a desired therapeutic outcome.Examples of selected parameters will be discussed further below.

Referring now to FIG. 3, in certain embodiments the present inventioncan act as a radioimmunology radiation dosimeter using quantification ofmeasured or detected internally administered radiation via the localizedsensor. To begin, a selected therapeutic treatment can be administeredto the subject (Block 300). The therapeutic radiation treatment may bean internally administered or radioimmunology treatment that may includegamma, beta, or alpha radiation (Block 301). The therapeutic radiationtreatment can be delivered systemically or locally as described above.The systemic delivery may also include the administration of radioactivegenetically engineered substances which target a cancerous tumor ordiseased or organ or tissue of interest. The radiation can be monitoredby an in situ sensor that is positioned in tissue in a target site inthe body. As such, the radiation proximate to the target tissue isdetected in vivo, (including adjacent to or within the tissue ofinterest) and is monitored over a selected time period (Block 310). Thetherapeutic treatment can be assessed based on the monitored radiationdata (Block 315). The assessment can include determining whether thetissue exhibits a change in biocellular, biokinetic, or biochemicalprocess, or exhibits a desired response, uptake, retention, signalstrength, or a non-response to the selected therapy. In radioimmunologytherapies, the amount of radiation which reaches the target site (thedesired treatment destination) can be quantified. That is, the radiationdose can be quantitatively evaluated based on the monitored detectedvalues to assess or confirm that a desired (typically therapeutic) doseat the diseased or targeted tissue was received at the target siteand/or that the appropriate lower dose was received away from thetargeted site (Block 320).

The term “tissue” includes all substances in the body, e.g., anaggregation of morphologically similar cells and intercellular matterperforming one or more functions in the body (such as, but not limitedto, muscle, arteries, veins, vessels, tissue, bone, bone marrow, and thelike) as well as serum, interstitial fluid or liquid. The liquid orfluid detection may be more typically measured with a fiber version of adetection or senor probe rather than a non-fiber version of the sensor.

In certain embodiments, a plurality of radiation sensors or sensingprobes can be positioned about different locations in the targetedregion to evaluate the distribution of the radiation dose across thisregion. In other embodiments, at least one radiation sensor can also bepositioned in normal tissue, sensitive tissue, or adjacent the targetsite to monitor the amount of radiation which is delivered thereto toattempt to reduce the likelihood that radiation is overdosed inundesirable amounts to undesired locations. This information can allowclinicians to refocus, adjust, or revise the strength or type of thetreatment (during or after a therapy session). For example, a number ofpharmaceutical products can be formulated into a correspondingradiolabeled version, which allows for the particular pharmaceutical tobe analyzed locally in its radiolabeled form. The radiolabeled versionhas the same or substantially similar pharmacological activity as theparent drug or compound.

Further, C-14 radiolabeled drugs have been used in the past to evaluateits physiologic impact on a subject during regulatory reviews to analyzemetabolic byproducts. Typically, these types of studies have used ascintillating fluid with urine or fecal samples or exhaled ¹⁴CO₂.

Examples of chemotherapeutic pharmaceutical products, which can beformulated with a C-14 tag, include antineoplastics such as alkylatingagents, nitrogen mustards, nitrosureas, antibiotics, hormonalantagonists or androgens, antiandrogens, antiestrogens,estrogen/nitrogen mixtures, estrogens, gonadotroopin releasing hormones,immunomodulators, and other appropriate therapeutic agents. Otherproducts not specifically listed may also be used as contemplated byembodiments of the present invention. Table 1 lists a few examples ofproducts, which can be radiolabeled for cancer treatments according tothe present invention. TABLE 1 Agent Manufacturer A. Alkylating agents 1. Myleran GlaxoSmithKline (Glaxo)  2. Paraplatin, platinol BristolMyers Squibb (BMS)  3. Temodar Schering B. Nitrogen Mustards  1. AlkeranGlaxo  2. Cytoxan BMS  3. Ifex BMS  4. Leuderan Glaxo C. Nitrosureas  1.BCNU BMS  2. CCNU BMS  3. Gliadel wafer Aventis D. Antibiotics  1.Adriamycin Pharmacia & Upjohn  2. Blenoxane BMS  3. Idamycin Pharmacia &Upjohn  4. Mithracin Bayer  5. Mutamycin BMS  6. Novantrone Immunex  7.Rubex BMX  8. Fludara Berlex  9. FUDR Roche 10. Thioguanine Glaxo 11.Xeloda Roche E. Hormonal Antagonists  1. Nilandron Aventis  2. TeslacBMS F. Antiandrogens  1. Casodex AstraZenaca  2. Eulexin Shering G.Antiestrogens  1. Arimedex AstraZenaca  2. Aromasin Pharmacia  3. FemaraNovartis  4. Nolvadex AstraZenaca H. Estrogen/Nitrogen mixture  1. EmcytPharmacia I. Estrogens  1. Estinyl Schering J. Gonadotroopin ReleasingHormones  1. Lupron TAP  2. Zoladex AstraZeneca K. Progestins  1. MegaceBMS L. Immunomodulators  1. Ergamisol Jansen M. Miscellaneous  1.Camptosar Pharmacia  2. DTIC Bayer  3. Etopophos BMS  4. Gemzar Lilly 5. Herceptin Genetech  6. Hydrea BMS  7. Intron A Scherling  8.Lysodren BMS  9. Navelbine Glaxo 10. Oncovin Lilly 11. Proleukin Chiron12. Rituxan IDEC 13. Roferon A Roche 14. Taxon BMS 15. Taxotere Aventis16. Velban Lelly 17. VePesid BMS

FIG. 4A illustrates one embodiment of a radiation detection system 10.As shown, the detection system 10 includes a radiation sensor 25configured for in vivo wireless (telemetric) operation as it resides ina subject such that, during operation, the sensor 25 is proximate to orcontacts tissue in the region of interest in the subject. The sensor 25is operably associated with a processor 50 which can direct theactivation of the sensor 25 and which can receive detected signalstelemetrically transmitted from the sensor 25. The processor 50 isoperably associated with computer program code or instructions 75 whichanalyze selected parameters associated with at least one of: (a) theuptake and/or retention of a radioactive or radiolabeled analyte and/ora radiolabeled biochemical constituent thereof in localized tissue; (b)the in vivo pharmacokinetics/pharmacodynamics of the radiolabeledanalyte and/or a radiolabeled biochemical constituent thereof; and/or(c) the dose amount of radiation received at the localized tissue froman internally administered therapeutic radiation dose. Each of theselected parameters correspond to a plurality of values or measurements(such as one or more predictor variables taken from a time-dependentmeasurement profile) of a data signal associated with the radiationdetected by the sensor 25 over a time period or periods of interest.

In certain embodiments, the sensor 25 is configured to be biocompatibleand operable as it resides in the body for a period of at least about 1day, and typically for at least about 1-3 weeks. In certain embodiments,the sensor 25 can reside in the body for about 1-3 months and isconfigured to be relatively non-invasive to the subject (so as to bebiosealed to the environment, substantially non-irritating orunobstructive to the subject and/or so as to not unduly interfere withnormal life activities).

As schematically shown in FIG. 4B, the sensor 25 can be mounted in ahousing such as catheter and/or or be a fiber optic probe configured forinsertion into the body and wired to an external operating system(represented by the solid lead lines drawn from the sensor to theprocessor). Such a system may be particularly suitable for short-term oracute positioning in the body and may be configured to collect datasimilar to the embodiment shown in FIG. 4A. The probe or catheter can beconfigured and sized to be positioned at the desired siteintraoperatively, intraperitoneally (where the tumor or targeted tissuesite is so located), subcutaneously, transcutaneously, or directinjection to the target site(s). In other embodiments, the catheter orprobe can be guided or inserted into a cavity or natural lumen. In anyevent, the housing, probe or catheter is guided into the body until thesensor 25 is positioned in the desired location(s) in the body. In theseembodiments, the sensor 25 may be hard-wired to (and powered by) theexternal system and activated by the processor 50 at desired monitoringtimes.

For certain embodiments, the system 10 may be a fiber-optic basedradiation detector with the sensor probe comprising a plurality orbundle of fibers to provide intended surface areas for improveddetectability. Light impeding cladding material may be placed over allbut a desired tip portion of the fiber(s) to define a desired effectiveactive detection surface area. One or more fibers (or a fiber bundle)may be employed. For example, a 2 mm fiber can be coupled directly to achannel multiplier head with about a 2.2 mm length exposed for activedetection to define an effective active surface area of about 0.17 cm².Suitable active surface areas may be in the range of between about 0.10cm²-1 cm². Examples of fiber optic sizes include those having a diameterbetween about 2 mm to about 250 μm. Other sizes may be used depending onthe application and number of fibers employed. As desired, an opposingend portion can be coated with a thin layer of aluminum or lightshielding material to shield it from ambient light as needed, ormeasurements can be obtained in a light reduced room.

An example of an intraoperative surgical probe is described in U.S. Pat.No. 6,076,009, the contents of which are hereby incorporated byreference as if recited in full herein. In other embodiments, the sensor25 can be configured as a wireless or telemetric implantable sensor 25as discussed in relation to FIG. 4A above. Examples of suitableimplantable sensors as will be discussed further below.

FIG. 5A is a schematic illustration of other embodiments of the presentinvention. As shown, the sensor 25 is implanted in a subject at adesired target region in a subject so as to reside in the subject on achronic basis for a desired period of time (typically between about 1day-3 months). The system 10′ includes a reader 60, which may be awireless reader configured to wirelessly or telemetrically activate orinitiate the activation of and reception of signals from the sensor 25(the signals including data corresponding to the detected radiation).Co-pending U.S. patent application Ser. No. 09/407,359 filed Sep. 29,1999, the contents of which are hereby incorporated by reference as ifrecited in full herein, includes descriptions of suitable telemetricconfigurations and sensors. As is also shown in FIG. 5A, theradiolabeled analyte 80 can be a liquid which can be formulated forinjection into the subject.

FIG. 5B illustrates another embodiment of the present invention. Asshown, the radiolabeled analyte 80 may be formulated for systemic ordirect injection, such as via syringe or IV injection. The system caninclude a photo multiplier tube (PMT) 154 in optical communication withthe sensor 25 and an amplifier 152. The system may also include amulti-channel scaler 150 and a computer 50.

The present invention can acquire data associated with the detectedradiation and generate at least one time-dependent measurement profileof the radioactivity in a localized region of the subject. Thetime-dependent profile can be analyzed to identify or quantify one ormore predictor variables or parameters which capture desired informationcorresponding to one or more of the efficacy, performance, activity,response or status of the radiolabeled substance in the body and/thetargeted or localized tissue.

Turning now to FIGS. 6A-6E, examples of parameters or predictorvariables and time-dependent profiles which can be analyzed or monitoredare illustrated. FIG. 6A illustrates that a monitored response time canbe individualized such that measurements are obtained over a periodduring which the detected radiation is above a predetermined thresholdvalue (the threshold value is represented by the broken line adjacentthe X axis). In other embodiments, the response or monitoring period canbe pre-determined (such as between about 0.1-0.25 to 1-3 hours or to 24hours or longer). As shown, radiation is detected over a period of time(t). The time at which the radiation is above a particular value (shownas the threshold value, but it may be at a higher value) can be definedas the time during which the local tissue is able to uptake, trap oraccumulate or retain the radiolabeled or radioactive analyte (t_(trap)).The detected radiation may have a peak at a particular time in theresponse cycle (t_(peak)). In addition, the radiation may increaseduring a portion of the response cycle (t_(inc)) and decrease for aperiod of time thereafter (t_(dec)). The rate of increase or decrease ortime to reach the peak or the lower threshold may also be calculatedbased on the monitored values. Further, the acceleration or decelerationor decay rate (either an average or at particular times during themonitored period) can be established.

For example, the energy from C-14 decay peaks at about 55 KeV. Generallydescribed, in the time-dependent measurement profiles, each “count” orpoint in the profile or curve can correspond to a pulse of charge, andthe pulse of charge can be quantified using a charge sensitive detector.In certain embodiments, signal to noise ratios can be enhanced invarious ways, such as by allowing for signal integration over short timewindows of about 1 μs so that dark counts are reduced. In certainembodiments, the time duration of the signal pulses can be about 10 nsor less.

One or a combination of parameters or appropriate predictor variablescan be correlated or statistically evaluated to determine the impact onclinical outcome or performance in the body. As such, the parameter ispredictive of a desired performance, response or status of the localizedtissue in the subject (or in other embodiments of the delivery and/orthe quantification of the amount of radioactive substance actuallydelivered to the targeted treatment site).

For example, if a subject has a relatively long trapping time, such thatit is able to retain the radiation above a certain level for greatertimes (either absolute or relative) than previously or in comparablesubjects or as established in clinical data, this capability mayrepresent a positive predictive factor. Similarly, if the decay rate isslow or the peak (or time to saturation) is reached later in theresponse cycle, this may also represent a positive predictive factor orthat a favorable treatment response is indicated. Other examples includelater uptake and a smaller decrease from a peak value after arepresentative time. For example, if the signal exhibits less than apredetermined percentage drop from peak or maximum radiation activityafter a representative time (such as 0.25 to 1-5 hours after initiationof the administration of the radiolabeled analyte to the subject), thismay represent a favorable predictive factor.

For monitoring based on [¹⁴C]glucose, or C-14 labeled glucosederivatives (such as dextraglucose), the biochemical processesassociated with the metabolism or glycolysis of the glucose may be suchthat the radiolabeled component is discharged from the body in as littleas 5-10 minutes from the time of administration, and the data collectionmay be carried out to obtain increased data points during a shortercollection time, such as, but not limited to, during the first 0.25hours, such as during the time period extending between about time equalabout 0 to about 15 minutes-1 hour post-initiation of the administrationof the radiolabeled glucose/glucose derivative.

FIG. 6C represents monitoring of the biological half-life (T_(1/2)).Biological half-life times greater than a predetermined time may be anadditional favorable or positive predictive factor. The presence ofseveral of the positive predictive factors may indicate a particularlyreliable indication of a favorable treatment opportunity.

FIG. 6B illustrates that the area under the curve can be used tocalculate the dose of radiation received at the targeted site. Otherdose correlation or calculation means can also be employed. FIG. 6Eillustrates that the signal can be monitored and mathematicallyintegrated and then a (first) derivative mathematically taken torepresent the rate of change of concentration over time associatedtherewith. For illustration, in the embodiment shown, the lineshape ofFIG. 6E corresponds to the derivative of the profile of FIG. 6A, albeitin a unitless manner without accounting for the amplitude values. Theactivity corresponds to the count (C) over time (taken in small pulsedintervals as noted above). Of course, other parameters andquantification or evaluation processing methods can be used depending onthe particular application and information desired.

FIG. 6D illustrates that the system can obtain a plurality of differentdata sets, each corresponding to a desired monitoring period. As shown,three different temporally separate response periods are monitored. Thethird response period is shown as having an increase in detectedradiation as may occur when an enhanced or favorable treatment isidentified. These monitoring procedures can be performed prior to eachtherapeutic treatment, or several times before a favorable treatmentwindow is indicated. The monitoring can also be done after steps aretaken to influence or induce the targeted region to be more receptive todrug uptake (such as by directing external radiation at the targetsite).

It is noted that relative or absolute values of the detected signal canbe used to assess the intensity or quantify the amount of radiation atthe site (such as by taking a measurement before radiation is introducedto have a baseline indication to cancel out background information or byusing the ratio of two measurements).

FIG. 6F is a flow diagram of a method (preferably carried out by acomputer program) for using at least one predictor variable taken from atime-dependent measurement profile associated with the uptake and/orretention of radiation in the tissue. The predictor variable can be aplurality of calculated kinetic factors to determine whether abiokinetic response (which can mean changes in the biological orphysiological function of the subject) is favorable in order to maketherapeutic treatment decisions according to embodiments of the presentinvention. As shown, at least one predictor variable (which can be aplurality of predictive kinetic factors) associated with the uptakeand/or retention of radiation is determined (Block 300). The predictivevariable can be one of those described above or other parameters. Themethod then assesses the metabolic activity of the subject (Block 305)and/or whether the biokinetic response of the subject is favorable(Block 310). If so, in certain embodiments then a desired treatment canbe delivered to the subject (Block 320). If not, then a treatment can bedelayed or postponed or altered (Block 330) to attempt to increase thechances for a favorable therapeutic response. The method may alsoconsider the available therapy types and select one which is more likelyto achieve a clinically satisfactory outcome based on tumor type,certain kinetic or activity based predictive factors, or other patientinformation (such as age, treatment number (such as whether it is aprimary or secondary or tertiary treatment)) or the like. Alternatively,or additionally, the metabolic evaluation (Block 305) can be used tostudy or evaluate pharmacokinetic data (Block 306) and/or to assess theefficacy of a planned or delivered therapy (Block 307).

The detection systems contemplated by embodiments of the presentinvention may be configured in several suitable configurations. Forexample, the system 10 can be configured: (a) as a fiber-based systemwith externally located operating electronics such as shown in FIG. 5Band 10A; (b) as a multiple-implantable component system such as shown inFIG. 9 (indirect detection that use optical fibers with scintillatorsthat can feed light back to a collective photodiode) and FIG. 10B(direct beta radiation such as with a detector crystal); (c) a singleimplantable unit telemetry linked to an external reader such as shown inFIG. 10C (semiconductor used as a direct detector that similar to FIG.10B can directly convert the beta into electron-hole pairs that areelectrically measured); and (d) a single implantable unit with anindirect detector such as shown in FIG. 7 (the body of the implantableunit is the scintillator and is in optical communication with aphotodiode). A combination of the systems or selected componentsdescribed herein may also be employed. In certain embodiments, aplurality of sensing probes (direct and/or indirect) can be used with acentral or single external reader to monitor radiation at more than onelocation in the body.

Generally stated, there are two primary means for measuring ionizingradiation using a solid-state detector: namely, direct and indirectconversion. As noted above, the radiation sensor 25 of embodiments ofthe present invention may be configured for direct or indirectdetection. In direct conversion, the ionizing radiation itself createsan electron-hole pair in a region of the detector, and these changes canbe separated by a biasing electric field and collected as a currentthrough or in the device. Indirect conversion converts ionizingradiation to light in a scintillator and the light is detected by themechanism involved in the pair production described above.

As such, the detection system 10 and/or the associated sensor(s) 25 maybe physically and/or operationally configured in a number of suitabledesigns. For example, referring now to FIG. 10A, the sensor 25 of thedetection system 10 may be configured for acute placement of apercutaneous or internally located scintillating fiber(s) that couplesto an externally located detector 10D. That is, the sensor 25 directlyrelays the light signal to a detector 10D located outside the body. Inthe embodiment shown in FIG. 10A, the external detector 10D comprisesthose components inside the broken line. Other configurations ofdetectors 10D may be employed. This embodiment may reduce the size andelectronic operational complexity of the portion of the device insertedor placed into the patient.

As shown in FIG. 10B, in other embodiments, a fully implantable sensorassembly 25 may be configured with at least one sensor head (probe body)25 s that is independently positionable in the body of the subject sothat it contacts the targeted tissue. The sensor or probe body 25 s isconnected to a processor body 25 p via one or more fibers or wires 25 wand can be (subcutaneously) implantable a distance away from the probebody 25 s typically closer to the surface of the skin. Althoughillustrated as subcutaneously implanted, the processor body 25 p mayalso be externally mounted onto the skin of the subject and secured inposition with an external biocompatible covering. The processor body 25p can be configured to include most of the wireless transmit/receivecircuitry and so that it communicates with an external reader 60. Theinternal processor body 25 p can include a differential receiver 25 ₁,an amplifier/pulse shaper 25 ₂, a modulator 25 ₃, and a loop antenna 25₄ that can be magnetically coupled to a like component in the externalreader 60. The processor body 25 p can also include other componentsconfigured to power the sensor 25 s and/or communicate or interface withthe external reader 60. The probe body or sensor 25 s can comprise theactive sensing component such as a detector crystal 25 _(s1) and acharge amplifier/bias network line, driver 25 _(s2). The external reader60 includes a telemetry antenna and the processor 50.

In still other embodiments, as shown in FIG. 10C, the sensor 25 is aunitary body that includes the active sensor, shown as a direct betaradiation detector 25 s, as well as the operational and communicationelectronics 25 e that is configured to wirelessly communicate with theexternal reader and collect the radiation data. The unitary body may behoused in a biocompatible sealed-glass or suitable material housing 25 cthat is configured for direct detection of the radiation andminiaturized and implantable into the target tissue. The supportelectronics 25 e can be positioned on a circuit substrate 25 sub. Theimplantable unit 25 may also include a ferrite core to promote externalcommunication operations. The radiation sensor 25 can be implanted inthe body of a subject via surgery, injection, or inserted through amedical trochar. The radiation sensor 25 can be miniaturized such assized at about 2-3 mm in width (or less) and about 10-20, and typicallyless than 25 mm in length. Each of the implantable versions shown inFIGS. 10B and 10C may be particularly suitable for chronic in vivoplacement.

The operating power for certain of the implantable sensor 25configurations may be provided by an inductive coupling of a RF fieldpositioned in the vicinity of the implantable sensor 25. This istypically provided by a reader 60 (FIG. 5A) which can generate thedesired power field and receive the signals from the sensor 25 (deviceswhich include both transmit and receive functions may be termed a“transponder”). Alternatively (or additionally), the implantable sensor25 may employ an internally mounted battery as a power source (notshown). See U.S. patent application Ser. No. 09/407,359 incorporated byreference above. In certain embodiments, the reader 60 (FIG. 5A) can beconfigured to transmit information as well as power to the sensor 25(for inductively powered models) and to receive the detected radiationsignals (i.e., a “two-way” system).

FIG. 7 illustrates an indirect conversion sensor 25. Turning now to FIG.7, an example of an alternate implantable radiation sensor 25 isillustrated. The radiation sensor 25 can be implanted in the body of asubject via surgery or inserted through a medical trochar. As before,the radiation sensor 25 can be miniaturized, such as sized at about 2-3mm in width (or less) and about 10-20 mm, and typically less than 25 mmin length. The radiation sensor 25 shown in FIG. 7 is configured tomeasure or detect ionizing radiation by generating analog or digitalsignals that represent the detected or measured radiation.

In certain embodiments, the sensor 25 can include a photodiode orsimilar semiconductor element as the active sensor. Examples of suitableactive sensors can include, but are not limited to, a silicon photodiodeoperating in photovoltaic mode, a silicon photodiode operating inreverse bias mode, silicon photodiode operating in avalanche mode, anavalanche photodiode (APD), an APD in Geiger mode, a silicon PIN diode,a charge coupled device (CCD), other photodiodes or radiation sensorscomposed of gallium arsenide, II-a natural and CVD diamond, GaN, SiC,CdZincT (“CZT”), and ionization chambers and miniature electronmultiplier and photomultiplier devices.

In the embodiment shown in FIG. 7, the body of the sensor 25 may bemolded into a desired geometry from a scintillating material 28. In theembodiment shown, a miniaturized elongated cylindrical body 25 b is usedto hold the internal circuitry. The inner and outer surfaces 25 i and 25o of the body 25 b include a reflective material 25 r. As shown, incertain embodiments, the entire perimeter of the body of the sensor 25is able to act as a scintillator. The reflective material 25 r may bepositioned to encase the outer and inner walls of the scintillatormaterial. The reflective material 25 r may be formed onto thescintillator material by various techniques such as vacuum deposition,coating, spraying, or the like. The reflective surfaces 25 r define theboundaries of the light guide or light channel 33 which, in operation,captures and directs the light created by the conversion of the ionizingradiation to at least one “impinging” or detection point 26 which doesnot have the reflective coating, which allows the light to travel out ofthe light channel 33 and into to at least one proximately positionedphoto detector 30.

As shown, the sensor 25 has two opposing light input points 26, each ofwhich is in optical communication with a respective photo detector, suchas one of the photodetectors 30. The photodetector 30 resides on acircuit substrate 32 on opposing sides of a line of symmetry extendingaxially along the body of the device. An index matching material can bepositioned between the light entrance surface of the photodiode 30 andthe exit portion of the light guide 26. The index matching material maybe formed onto the exit portion of the light guide 26 or maybe formed asa film or pad held therebetween. The index matching material may beselected so that its refractive index is close to the average of theindices of the scintillating material and the material forming theentrance or front surface of the photodiode 30 f (and typically suchthat it is substantially different from air). As noted above, forcertain embodiments, the radiation sensor 25 is configured to detectpeak radiation on the level of about 55 KeV. The radiation sensor may beoperated to provide about 20-1000 or more counts per second. Forexample, for 166 nCi/cc, and about a 2 cm detector (active surface)region, the radiation sensor 25 may provide about 30 counts per second.

A ferrite core inductor 40 is positioned in the cavity of the sensorbody 25 b away from the photodiode(s) 30. Additional support orcomponents 35 may be mounted to the circuit substrate to provideoperational or mechanical support therefor.

It is noted that other suitable geometries can also be used to form thelight guide or channel(s) 33. FIG. 8A illustrates a single photodiode 30located at a light exit portion 26 at one end of the light guide channel33. FIG. 8B illustrates a light exit portion 26 at an end portion of thebody of the sensor 25 b.

FIG. 9A illustrates that a sensor 25′ with multiple radiation probes 25p, each on a flexible arm 25 arm can be used to detect at differentregions in the desired region of the body. The radiation sensor 25′ maybe implantable with the center body 25 s housing the ferrite coreinductor (acting as a power/transmitting satellite body) and the endprobes 25 p providing the lightguides and scintillators and beingconnected to the primary body. The arms of the probes 25 arm can becovered in reflective material to channel the light to selectedphotodiodes in the center body 25 s (the probes being configured so thatthey are each in optical communication with a selected photodiodetherein). As noted before, the radiation sensor 25, 25′ may also bepositioned on a catheter or probe. In this embodiment, the sensor(s) 25,25′ may reside on a perimeter portion thereof such that, in position inthe body, each (the active part of the probe or sensor) is exposed tothe desired target region in the subject so as to allow the radiation toactivate the scintillator material.

FIG. 9B illustrates that a sensor 25″ may also include a sensor body 25b with a plurality of fiber optic segments or leads 125 positioned inthe tumor mass.

The fiber optic leads 125 may be coated with a scintillator material asnoted above and used to collect, capture, and relay light scintillatedfrom different regions of the target site to the sensor body 25 b. Eachlead 125 may be polled separately of the light funneled concurrently toone or more active sensing regions in the sensor body 25 b which may beconfigured with or in optical communication with a PMT, photo-avalanchedetector or the like.

The present invention is explained in greater detail in the followingnon-limiting Examples.

EXAMPLES

A fiber optic probe suitable for transcutaneous placement was used witha photomultiplier tube for detection of beta radiation from C-14 labeledglucose (available from Amersham Pharmacia Biotech). A commerciallyavailable channel multiplier tube (from Perkin Elmer, model C943 P) wasused with a small array of scintillating fibers (from Bicron). Thefibers were packed loosely into a retaining collet and fixed in placewith epoxy (EPO-TEK 301). The sample surface was then polished to removeany residual epoxy from the faces of the fibers. The active area of thefiber bundle was about 0.17 cm², and typically the active surface is atleast about 0.10-1 cm². The opposite end of the fiber bundle was matedto the surface of the channel multiplier with optical cement. The systemwas assembled with a power supply, the channel multiplier and the fiberbundle detector.

The C-14 labeled glucose was used at a concentration of about 50-200μCi/ml and the tips of the fibers were exposed to the solution in alight-tight enclosure. Current pulses from the channel multiplier due tobeta events were amplified (using amplifier model A101 from Amptek) andsent as TTL pulses. A LabView device (from National Instruments) wasused to record or monitor the counts per time. No pulse-height analysiswas performed on the counts from the channel multiplier. About 850counts per second were recorded whereas the background count was belowabout 25 counts per second.

The energy spectrum from C-14 decay peaks at 55 KeV. The average rangeof the C-14 beta in water is believed to be about 50 μm. Using theeffective surface area of the fiber bundle, the count rate observed wasconsistent with an effective detection thickness of 50 μm. That is, theattenuation of betas reaching the fibers due to the water is equivalentto having the listed activity present in a uniform layer on the face ofthe fiber that is 50 μm thick.

The detector sensitivity can be impacted by the amount of surface area.In operation, each count corresponds to a pulse of charge and thischarge can be quantified using a charge sensitive detector. The signalto noise ratio may be enhanced by allowing for signal integration overshort time windows, in the range of 1-100 μs, and more typically closerto the lower end of the range so that dark counts are reduced. The timeduration of the signal pulses can be less than about 10 ns.

For in vivo evaluations, a 2 mm fiber bundle may be inserted intoposition via a small incision at an entry site. A 13 gauge needle, witha solid removable component, can be inserted into the incision. Thesolid component can be removed and replaced with the fiber or fiberbundle. Once in place, a retention component can be applied to secure itin position (suture, surgical glue or the like) and the needle removed.The labeled glucose can be injected into the tail vein of test animals(such as rats) in a single bolus. The total activity may range fromabout 1-10 mCi based on the SNR noted above. After several passes in theblood stream, tissue levels of C-14 will rise (approximately 2-3 minutesafter administration). The radiation detected by the fiber bundle andrelayed to the photomultiplier tube can be monitored until theconcentration drops to about 10% of the initial value in counts persecond to evaluate individual differences in bio or pharmacokineticsbetween subjects and tumors.

Experiments using single or dual probe sensors have been used to obtainin vivo response data. The radiolabeled analytes used in the in vivoexperiments included ¹⁴C-2DG (C-14 labeled 2-deoxyglucose) and ¹⁴C-5FU(C-14 labeled 5-Fluorouracil, a chemotherapeutic cytotoxic agent).

FIG. 11A illustrates a response profile graph (an integrated counts(above threshold) over time profile) taken over a monitored time periodof about 85 minutes (study #2). The counts were taken on a thirtyseconds/sample count time frame. In this experiment, a fiber optic probewas positioned subcutaneously in “normal” or non-cancerous tissue in theback of a Fisher 344 rat. A dose of 50 μCi of ¹⁴C-2DG was injected inthe tail vein. The data was monitored for about 85 minutes. As shown,the counts increased after the injection as reached a plateau at about10 minutes from the time of injection (about 35 minutes into themonitoring period). The initial portion of the graph has values thatrepresent “baseline” or dark current. At about point “70” (correspondingto about 35 minutes), the injection is given and uptake continues untilit plateaus around point “90” (corresponding to about 45 minutes).

FIG. 11B-11C illustrate graphs of data obtained using two probes, eachplaced subcutaneously in normal tissue of a 190 gram female Fisher 344rat, one placed in the flank/inguinal and the other in the scapula(study #4). The graph plots μCi/ml over time at 90 second per mark withthe upper line corresponding to the data obtained at the scapula and thelower line corresponding to the data obtained at the flank. In thisexperiment, a bolus of 200 μCi of ¹⁴C 2-DG was administered viaintra-peritoneal (IP) injection. The data was monitored for about 96minutes. As shown, higher concentrations were obtained in the scapularegion compared to the flank region. The data supports thatpharmacokinetic modeling of in vivo concentration data is feasible.

FIG. 11C is a graph of a pharmacokinetic model-fit of the flank normaltissue data (from the inguinal region) of FIG. 11B versus time (μCi/mlversus time in minutes). The triangulated points represent observed dataand the line represents the predicted values. As shown, there is asignificant ramp up in the value of the detected signal or counts duringthe first 10 minutes, tapering to a gradual slope uptake in the 10-30minute range, followed by a substantial level region in the curve atabout 35 minutes that extends to just over the 60 minute range,whereupon the line is predicted to taper down. The peak or maxima pointin the graph is reached in the 20-50 minute range according to theobserved points on the graph. FIG. 11C used a one compartmental PK modelto generate the predicted data with 1st order input and 1st orderelimination kinetics. This statistical model was used to model theobserved values obtained from the flank/inguinal probe versus that whichcan be predicted using a model of the previously stated characteristics.Other statistical functions may also be used to develop a predictivemodel. Departures from the model may be used to evaluate tumor statussuch as growth, remission, or kill and/or irregular metabolic orresponse behavior.

FIG. 11D is a graph of two other studies, identified by D#2 and D#3.Each of these studies used 200 μCi of ¹⁴C-2DG administered via an IV toa 180 g rat to monitor the number of integrated counts obtained per 90seconds in a sampling period (90 seconds per each indicated mark on thetime axis). As shown, two probes were used to gather response data bothin normal (D#2N, D#3N) and tumor (D#2T, D#3T) tissue.

FIG. 12A is a graph of a response profile of data in two locations in atumor bearing 270 g Fisher 344 rat, obtained via a dual probe testset-up (study #5). Again, one of the two probes was positionedsubcutaneously in the scapular tissue (in a tumor) and the other in theflank (normal tissue) of the rat. A dose of 250 μCi of ¹⁴C labeled 5FUwas administered via intraperitoneal injection. Data was monitored forabout 100 minutes. FIG. 12A is a graph of the concentration of theradiolabeled analyte (μCi) over time (minutes) and illustrates that¹⁴C-5FU is relatively slowly absorbed into the flank tissue and scapulartumor after the injection. The concentration and uptake profiles of the¹⁴C-5FU are similar for both locations. The uptake profile is consistentwith results presented by Mahteme et al., Anti-Cancer Res, 18:943-50,1998 (describing an autoradiographic study in the rat). As shown in FIG.12A, the ¹⁴C concentrations continue to rise after about 90-100 minutesfrom the time of injection.

FIG. 12B is a graph of a response profile of concentration (μCi) overtime (minutes) of a 120 μCi dose of ¹⁴C-5FU administered via an IV inthe tail vein in a 300 gram Fisher 344 rat (study #6). Again, two probeswere subcutaneously placed in the rat, one in the flank (in tumortissue) and the other in normal tissue at the scapula. This subject wasmonitored about 70 minutes after injection. This graph illustrates thatthe ¹⁴C-5FU uptake is measurable or detectable shortly after theinjection and that the concentrations peak after within about 10-30minutes after dosing. The upper line represents the flank (tumor tissue)and the lower line represents the normal scapula tissue. Comparing thetwo lines in the graph, it is shown that in this experiment, the ¹⁴Cconcentration level peaks earlier in the tumor tissue than in the normaltissue.

It is anticipated that a glucose based radiolabeled analyte can beadministered multiple times during a treatment period to evaluatemetabolic activity and/or tumor response. In addition, a radiolabeledglucose (or other metabolite) can be administered along with atherapeutic agent (which may also be radiolabeled), typically each atdifferent times.

In summary, in certain embodiments, the present invention may be used toassess metabolic response or activity and/or may help identify morefavorable treatment periods or a subject's likely affinity orsensitivity to a drug before a therapeutic dose is administered. Thedata can be obtained in substantially real time via intermittent,episodic, or substantially continuous monitoring during desiredmonitoring periods to provide information on the biological,physiological, and/or metabolic behavior of one or more target regionsof interest. Such data may be employed to assess (a) single orcombination therapies (such as which therapy should precede the other orwhether both should be delivered concurrently or proximate to the other,and the like); (b) pharmacokinetics/pharmacodynamics; (c) alterations inor status of metabolic activity or function; (d) tumor response orstatus; and (e) drug behavior in drug discovery programs or pre-clinicalor clinical trials.

Unlike conventional treatments, where empirical protocols on the timingand the toxicity of the planned treatment can guide deliveries ofcytotoxic agents which may be more damaging to normal tissue than to anypositive treatment impact on the malignant cell population, certainembodiments of the present invention can allow for customized treatmentsbased on the dynamic changes during treatment that occurs within amalignant cell population. Making this information available toattending physicians and clinicians can allow them to exploit therevealed differences between malignant and normal cells, and henceimprove the treatment procedures to achieve better outcomes.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims. In the claims, where used, means-plus-function clause areintended to cover the structures described herein as performing therecited function and not only structural equivalents but also equivalentstructures. Therefore, it is to be understood that the foregoing isillustrative of the present invention and is not to be construed aslimited to the specific embodiments disclosed, and that modifications tothe disclosed embodiments, as well as other embodiments, are intended tobe included within the scope of the appended claims. The invention isdefined by the following claims, with equivalents of the claims to beincluded therein.

1. A system for detecting in vivo pharmacokinetic, pharmacodynamicand/or metabolic activity, comprising: at least one radiation sensorconfigured to detect in vivo beta radiation at least intermittently overa period of time, the at least one sensor adapted to be positioned insolid tissue, and configured to detect the beta radiation as it isemitted in response to an administered analyte as the analyte isbiochemically processed by the body, wherein the analyte comprises atleast one of the following: radiolabeled glucose, a radiolabeled glucoseconstituent, and a radiolabeled glucose derivative; and a processoroperably associated with the at least one radiation sensor andconfigured to receive data associated with the detected radiation fromthe at least one sensor, wherein said processor is configured toelectronically monitor selected in vivo parameters associated with oneor more of the uptake, processing, and retention of at least one of theradiolabeled glucose, the radio labeled glucose constituent and theradiolabeled glucose derivative in the targeted localized solid tissuebased on the data received from the at least one sensor.
 2. A systemaccording to claim 1, wherein the radiolabel comprises C-14 (carbon 14),and wherein the processor includes a computer readable storage mediumhaving computer readable program code embodied in said medium, saidcomputer-readable program code comprising computer readable program codefor monitoring selected in vivo parameters associated with one or moreof the uptake, processing, and retention of the C-14 labeled glucose,C-14 labeled glucose constituent or C-14 labeled derivative in the atleast one targeted localized solid tissue.
 3. A system according toclaim 1, wherein the sensor is configured as an implantable telemetricsensor adapted for chronic implantation in solid tissue proximate atumor site, and wherein the processor is configured to evaluate themetabolic activity of the tumor site.
 4. A system according to claim 1,wherein the processor is held in a remote housing, and wherein the atleast one sensor is configured to wirelessly transmit signals associatedwith the in vivo detected radiation to the processor over a periodextending from at least about 1 week.
 5. A system according to claim 4,wherein the at least one sensor is inductively powered and configured towirelessly transmit signals to the associated processor with the in vivodetected radiation over a desired investigational period.
 6. A systemaccording to claim 1, wherein the at least one sensor is a plurality ofdiscrete spatially separated sensors, including first and second sensorsthat are adapted to detect radiation emitted from respective first andsecond spatially separate locations in the body.
 7. A system accordingto claim 6, wherein the first location is associated with normal ornon-diseased tissue and the second location is associated with diseased,impaired, abnormal, or cancerous tissue.
 8. A system according to claim1, wherein the radiolabel comprises C-14, the system further comprisinga remote reader configured to communicate with the at least one sensor,the reader comprising the processor and being configured toprogrammatically evaluate selected predictive variables or parametersassociated with at least one of the uptake and retention of at least oneof the C-14 labeled glucose, the C-14 labeled glucose constituent, andthe C-14 labeled glucose derivative in the localized tissue to determineat least one of the following: the biological half life thereof, theamount of time the detected radiation is above a predetermined thresholdlevel in the solid tissue, the amount of time that the radiationdetected is increasing in the solid tissue, the peak value of thedetected radiation in the solid tissue, the time at which the peakradiation level occurs in the solid tissue, and the decay rate of thedetected radiation in the solid tissue.
 9. A system according to claim1, wherein the radiolabel comprises C-14, and wherein the processor isconfigured to determine the concentration of at least one of the C-14labeled glucose, the C-14 labeled constituent and the C-14 labeledderivative in the at least one localized region of interest.
 10. Asystem according to claim 1, wherein the processor is configured todetermine a time-dependent profile of emitted radiation in the solidtissue.
 11. A system according to claim 1, wherein the radiolabelcomprises C-14, and wherein said at least one sensor is configured todetect radiation related to biochemical processing of at least one ofC-14 labeled 2-deoxyglucose and a C-14 labeled constituent thereof. 12.A system according to claim 1, wherein the radiolabel comprise C-14, andwherein said at least one sensor is configured to detect radiationrelated to internal activity of C-14 labeled dextraglucose and a C-14labeled constituent thereof.
 13. A system according to claim 1, whereinthe radiolabel comprises C-14, and wherein said sensor is configured todetect radiation related to internal activity of an administered C-14labeled glucose or C-14 glucose derivative, wherein the C-14 labeledglucose or glucose derivative is selected to have a modified glucosemolecular chemical structure that is biocompatible and can bebio-chemically processed by the body.
 14. A system for analyzing an invivo response of a subject, comprising: an implantable radiationdetector for detecting radiation present in at least one localized solidtissue region of interest in a subject associated with internal activityof an administered quantity of an analyte comprising at least one ofC-14 labeled glucose, a C-14 labeled glucose constituent, and a C-14labeled glucose derivative, in the at least one solid tissue region ofinterest over a desired time interval of interest; and a reader incommunication with the implantable detector for collecting radiationdata from the detector associated with the detected radiation todetermine at least one of the following: the in vivo dynamic, kinetic,and metabolic response of the subject.
 15. A system according to claim14, wherein the detector is configured to detect the concentration ofthe analyte in the at least one localized region of interest.
 16. Asystem according to claim 14, wherein said detector is configured todetect radiation related to in vivo biochemical processing of C-14labeled 2-deoxyglucose or a C-14 labeled derivative of 2-deoxyglucose.17. A system according to claim 14, wherein said detector is configuredto detect radiation related to the internal activity of at least one ofC-14 labeled dextraglucose and a C-14 labeled constituent thereof
 18. Asystem according to claim 14, wherein said detector is configured todetect radiation related to the internal activity of an administeredC-14 labeled glucose derivative, wherein the C-14 labeled glucosederivative is selected to have a modified glucose molecule chemicalstructure that is biocompatible and can be bio-chemically processed bythe body.
 19. A system according to claim 14, the reader furthercomprising a processor having a computer readable storage medium havingcomputer readable program code embodied in said medium, saidcomputer-readable program code comprising computer readable program codeconfigured to receive and analyze signals associated with thebiochemical processing of at least one of the C-14 labeled glucose, theC-14 labeled glucose constituent and the C-14 labeled glucose derivativeand a corresponding radiolabeled biochemical constituent thereof in thebody.
 20. A system according to claim 14, wherein the sensor ischronically implanted proximate a tumor treatment site, and whereinreader is configured to provide assess a likelihood of receptiveness ofa tumor treatment site to a therapeutic cytotoxic treatment based on themonitored radiation data in the solid tissue proximate the tumor site.21. A system according to claim 14, wherein the reader is configured torepetitively obtain radiation measurement data in the solid tissue insubstantially real time over a desired monitoring window to evaluatechanges in physiological, biological and/or metabolic behavior of atumor treatment site.
 22. A system for analyzing an in vivo response ofa subject, comprising: a radiation detector for detecting in vivoradiation present in at least one localized solid tissue region ofinterest in a subject associated with internal activity of anadministered quantity of C-14 labeled 2-deoxyglucose in the at least onesolid tissue region of interest over a desired time interval ofinterest; and a reader in communication with the implantable detectorfor collecting radiation data from the detector associated with thedetected radiation to determine at least one of the following: the invivo dynamic, kinetic, and metabolic response of the subject.
 23. Asystem according to claim 22, wherein the reader is configured to assesswhether a tumor treatment site is likely to be receptive to atherapeutic cytotoxic treatment based on the monitored radiation data inthe solid tissue proximate the tumor site.
 24. A system according toclaim 22, wherein the reader is configured to repetitively obtainradiation measurement data in substantially real time over a desiredmonitoring window to evaluate changes in physiological, biologicaland/or metabolic behavior of a tumor treatment site.
 25. A system foranalyzing an in vivo response of a subject, comprising: a radiationdetector for detecting in vivo radiation present in at least onelocalized solid tissue region of interest in a subject associated withinternal activity of an administered quantity of a C-14 labeled glucosederivative in the at least one solid tissue region of interest over adesired time interval of interest, wherein the glucose derivative isselected so that it has a modified glucose molecular chemical structurethat is biocompatible and can be bio-chemically processed by the body;and a reader in communication with the implantable detector forreceiving and analyzing radiation data from the detector associated withat least one of the C-14 labeled glucose derivative and a C-14 labeledbiochemical constituent thereof to determine at least one of thefollowing: the in vivo dynamic, kinetic, and metabolic response of thesubject.
 26. A system according to claim 25, and wherein the detectedradiation is from solid tissue proximate a tumor site.
 27. A systemaccording to claim 25, wherein the detector and reader operate proximatein time to and before a planned therapeutic treatment.
 28. A systemaccording to claim 26, wherein the reader is configured to provide apredictive indication of a receptiveness of the tumor site to atherapeutic cytotoxic treatment based on the monitored radiation data inthe solid tissue proximate the tumor site.
 29. A system according toclaim 25, wherein the reader is configured to repetitively obtainradiation measurement data in substantially real time over a desiredmonitoring window to evaluate changes in physiological, biologicaland/or metabolic behavior of a tumor treatment site.
 30. A system foranalyzing in vivo metabolic activity of a subject undergoing treatmentfor cancer, comprising: detection means for detecting metabolic activityin vivo based on levels of radiation present in localized tissue in thesubject over a time interval of interest in response to administrationof a radiolabled glucose or glucose derivative; and analyzing means forelectronically analyzing the detected radiation data to determine the invivo metabolic kinetic activity of the subject.